Reconfigurable dickson star switched capacitor voltage regulator

ABSTRACT

The present disclosure shows a reconfigurable Dickson Star SC regulator that can support multiple conversion ratios by reconfiguring between various modes. The reconfigurable Dickson Star SC regulator is designed to reduce the number of redundant capacitors by reusing capacitors and switches across multiple modes of operation (across multiple conversion ratios). The present disclosure also shows a hybrid (e.g., two-stage) voltage regulator.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims benefit of the earlier filing date, under 35U.S.C. § 119(e), of U.S. Provisional Application No. 62/324,091, filedon Apr. 18, 2016, entitled “RECONFIGURABLE DICKSON STAR SWITCHEDCAPACITOR VOLTAGE REGULATOR”, which is herein incorporated by referencein its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was made with government support under 1353640 and1519788 awarded by the National Science Foundation (NSF). The governmenthas certain rights in the invention.

TECHNICAL FIELD

The present disclosure relates to apparatuses, systems, and methods forproviding a reconfigurable Dickson Star switched capacitor voltageregulator and/or providing a hybrid (e.g., two-stage) voltage regulator.

BACKGROUND

There is a strong demand to reduce the size of electronic systems. Thesize reduction is especially desirable in mobile electronics where spaceis a premium, but is also desirable in servers that are placed in bigdata centers since it is important to squeeze in as many servers aspossible in a fixed real estate.

One of the largest components in electronic systems includes voltageregulators (also referred to as power regulators). Power regulatorsoften include a large number of bulky off-chip components to delivervoltages to integrated chips, including processors, memory devices(e.g., a dynamic read access memory (DRAM)), radio-frequency (RF) chips,WiFi combo chips, and power amplifiers. Therefore, it is desirable toreduce the size of the voltage regulators in electronic systems.

Power regulators include semiconductor chips, such as a DC-DC regulatorchip, that deliver power from a power source (e.g., a battery) to anoutput load. The output load can include a variety of integrated chips(e.g., an application processor, a DRAM, a NAND flash memory) in anelectronic device. To efficiently deliver power, a voltage regulator canuse a “buck” topology. Such a regulator is referred to as a buckregulator. A buck regulator transfers charges from the power source tothe output load using an inductor. A buck regulator can use powerswitches to connect/disconnect the inductor to one of multiple voltages,thereby providing an output voltage that is a weighted average of themultiple voltages. A buck regulator can adjust the output voltage bycontrolling the amount of time the inductor is coupled to one of themultiple voltages.

Unfortunately, a buck regulator is not suitable for highly integratedelectronic systems. The conversion efficiency of a buck regulatordepends on the size of the inductor, in particular when the powerconversion ratio is high and when the amount of current consumed by theoutput load is high. Because an inductor can occupy a large area and isbulky to integrate on-die or on-package, existing buck regulators oftenuse a large number of off-chip inductor components. This strategy oftenrequires a large area on the printed circuit board, which in turnincreases the size of the electronic device. The challenge isexacerbated as mobile system-on-chips (SoCs) become more complex andneed increasingly larger number of voltage domains to be delivered bythe voltage regulator.

SUMMARY

Some embodiments of the disclosed subject matter include a voltageregulator for regulating an input voltage at an input terminal to anoutput voltage at an output terminal. The regulator includes a capacitormatrix having a first capacitor sub-matrix and a second capacitorsub-matrix. The regulator also includes a switch matrix having a firstswitch sub-matrix, a second switch sub-matrix, a third switchsub-matrix, a fourth switch sub-matrix, and a fifth switch sub-matrix. Acapacitor in the first capacitor sub-matrix is coupled to the outputterminal through an associated switch in the first switch sub-matrix andis further coupled to a ground terminal through an associated switch inthe second switch sub-matrix. A capacitor in the second capacitorsub-matrix is coupled to the output terminal through an associatedswitch in the third switch sub-matrix and is further coupled to theground terminal through an associated switch in the fourth switchsub-matrix. Also, the fifth switch sub-matrix has an N number ofswitches arranged in series between the input terminal and the outputterminal, and each switch in the fifth switch sub-matrix is connected toan associated capacitor in the first capacitor sub-matrix and anassociated capacitor in the second capacitor sub-matrix. A K number ofswitches in the fifth switch sub-matrix that are closest to the inputterminal are turned on to reconfigure the voltage regulator to provide aconversion ratio of (N−K):1, wherein K is a non-negative value less thanN.

In one or more embodiments disclosed herein, the switch matrix isconfigured to alternate between a first configuration and a secondconfiguration at a predetermined duty-cycle while keeping the K numberof switches turned on in order to regulate the input voltage to theoutput voltage at the conversion ratio of (N−K):1.

In one or more embodiments disclosed herein, one of the K number ofswitches is configured to parallelize one capacitor in the firstcapacitor sub-matrix and one capacitor in the second capacitorsub-matrix that are connected to the one of the K number of switches.

In one or more embodiments disclosed herein, a first switch in thesecond switch matrix coupled to the one capacitor in the first capacitorsub-matrix and a second switch in the fourth switch matrix coupled tothe one capacitor in the second capacitor sub-matrix are controlledusing a same switch signal.

In one or more embodiments disclosed herein, a first switch in the firstswitch matrix coupled to the one capacitor in the first capacitorsub-matrix and a second switch in the third switch matrix coupled to theone capacitor in the second capacitor sub-matrix are controlled using asame switch signal.

In one or more embodiments disclosed herein, K is zero.

In one or more embodiments disclosed herein, K is N−1.

In one or more embodiments disclosed herein, K is a value in a range of0 and N−1.

In one or more embodiments disclosed herein, a number of switches in thefifth switch sub-matrix is N.

Some embodiments of the disclosed subject matter include a voltageregulator for regulating an input voltage at an input terminal to anoutput voltage at an output terminal. The regulator includes a capacitormatrix having a first capacitor sub-matrix and a second capacitorsub-matrix. The regulator also includes a switch matrix having a firstswitch sub-matrix, a second switch sub-matrix, and a third switchsub-matrix. One switch in the first switch sub-matrix is coupled to twoassociated capacitors in the first capacitor sub-matrix. One switch inthe second switch sub-matrix is coupled to two associated capacitors inthe second capacitor sub-matrix. The third switch sub-matrix has an Nnumber of switches arranged in series between the input terminal and theoutput terminal, and each switch in the third switch sub-matrix isconnected to an associated capacitor in the first capacitor sub-matrixand an associated capacitor in the second capacitor sub-matrix. A Knumber of switches in the first switch sub-matrix and the second switchsub-matrix, excluding a top switch in the first switch sub-matrix thatis connected to the input terminal, that are closest to the inputterminal are turned on to reconfigure the voltage regulator to provide aconversion ratio of (N−K):1, wherein K is a non-negative value less thanN.

In one or more embodiments disclosed herein, a K number of switches inthe third switch sub-matrix, excluding a top switch in the third switchsub-matrix that is connected to the input terminal, are turned off toreconfigure the voltage regulator to provide the conversion ratio of(N−K):1.

In one or more embodiments disclosed herein, the switch matrix isconfigured to alternate between a first configuration and a secondconfiguration at a predetermined duty-cycle while keeping the K numberof switches in the third switch sub-matrix turned on in order toregulate the input voltage to the output voltage at the conversion ratioof (N−K):1.

In one or more embodiments disclosed herein, when K is an odd number,the top switch in the third switch sub-matrix is turned off in both thefirst configuration and the second configuration, and wherein when K isan even number, the top switch in the first switch sub-matrix is turnedoff in both the first configuration and the second configuration.

In one or more embodiments disclosed herein, each capacitor in the firstcapacitor sub-matrix is coupled to the ground terminal through a firstswitch and is coupled to the output terminal through a second switch.

In one or more embodiments disclosed herein, each capacitor in thesecond capacitor sub-matrix is coupled to the output terminal through athird switch and is coupled to the ground terminal through a fourthswitch.

Some embodiments of the disclosed subject matter include an apparatus.The apparatus includes a means for reconfiguring a voltage regulator tomodify a conversion ratio from N:1 to (N−K):1, wherein K is anon-negative value less than N.

In one or more embodiments disclosed herein, the voltage regulator is aDickson Star voltage regulator.

Some embodiments of the disclosed subject matter include a voltageregulator configured to receive a first voltage signal and provide afinal voltage signal based, at least in part, on the first voltagesignal. The voltage regulator includes a switched-inductor regulatorconsisting of an inductor, wherein a first terminal of the inductorcomprises an input terminal of the switched-inductor regulatorconfigured to receive the first voltage signal, and a second terminal ofthe inductor comprises an output terminal of the switched-inductorregulator configured to provide an intermediate voltage signal. Thevoltage regulator includes a step-down regulator comprising an inputterminal configured to receive the intermediate voltage signal from theoutput terminal of the switched-inductor regulator, a switch matrix, aplurality of capacitors, and an output terminal, configured to providethe final voltage signal. The voltage regulator also includes a controlmodule configured to cause the switch matrix in the step-down regulatorto alternate between a first configuration and a second configuration toarrange the plurality of capacitors in a first arrangement and a secondarrangement, respectively, with a predetermined duty cycle, thereby alsoduty-cycling the inductor in the switched-inductor regulator.

In one or more embodiments disclosed herein, the switched-inductorregulator is switchless.

In one or more embodiments disclosed herein, when the switch matrix isin a first configuration, the intermediate voltage signal is at a firstvoltage level, and when the switch matrix is in a second configuration,the intermediate voltage signal is at a second voltage level.

In one or more embodiments disclosed herein, the first voltage level isa first fractional multiple of the final voltage signal, and wherein thesecond voltage level is a second fractional multiple of the finalvoltage signal.

In one or more embodiments disclosed herein, the step-down regulatorcomprises a Dickson Star switched capacitor regulator.

In one or more embodiments disclosed herein, the Dickson Star switchedcapacitor regulator comprises a reconfigurable Dickson Star switchedcapacitor regulator.

Some embodiments of the disclosed subject matter include a voltageregulator configured to receive a first voltage signal and provide afinal voltage signal based, at least in part, on the first voltagesignal. The voltage regulator includes a switched-inductor regulatorconsisting of an inductor, wherein a first terminal of the inductorcomprises an input terminal of the switched-inductor regulatorconfigured to receive the first voltage signal, and a second terminal ofthe inductor comprises an output terminal of the switched-inductorregulator configured to provide an intermediate voltage signal. Thevoltage regulator includes a step-down regulator having an inputterminal configured to receive the intermediate voltage signal from theoutput terminal of the switched-inductor regulator, and an outputterminal configured to provide the final voltage signal. The voltageregulator also includes a first switched capacitor regulator module. Thefirst switched capacitor regulator module has a switch matrix comprisinga first switch configured to couple the first switched capacitorregulator module to the input terminal of the step-down regulator, and aplurality of capacitors. The voltage regulator also includes a secondswitched capacitor regulator module. The second switched capacitorregulator includes a switch matrix comprising a second switch configuredto couple the second switched capacitor regulator module to the inputterminal of the step-down regulator, and a plurality of capacitors. Thevoltage regulator also includes a control module configured to cause theswitch matrix in the first switched capacitor regulator module toalternate between a first configuration and a second configuration toarrange the plurality of capacitors in the first switched capacitorregulator module in a first arrangement and a second arrangement,respectively, with a first duty cycle, cause the switch matrix in thesecond switched capacitor regulator module to alternate between a thirdconfiguration and a fourth configuration to arrange the plurality ofcapacitors in the second switched capacitor regulator module in a thirdarrangement and a fourth arrangement, respectively, with the first dutycycle, and cause the first switch and the second switch to alternatelycouple the first switched capacitor regulator module and the secondswitched capacitor regulator module at a second duty cycle.

In one or more embodiments disclosed herein, the first switchedcapacitor regulator module and the second switched capacitor regulatormodule operate out-of-phase.

In one or more embodiments disclosed herein, the first switchedcapacitor regulator module and the second switched capacitor regulatorcomprise an identical switched capacitor regulator topology.

In one or more embodiments disclosed herein, alternately coupling thefirst switched capacitor regulator module and the second switchedcapacitor regulator module at the second duty cycle causes duty-cyclingof the inductor in the switched-inductor regulator at the second dutycycle.

In one or more embodiments disclosed herein, the second duty cycle is0.5.

In one or more embodiments disclosed herein, the control module isconfigured to determine a time instance at which to begin alternatecoupling of the first switched capacitor regulator module and the secondswitched capacitor regulator module to provide a desired duty cycle ofthe switched-inductor regulator.

In one or more embodiments disclosed herein, the inductor is provided asa discrete component on-package or on-board.

Some embodiments of the disclosed subject matter include an electronicsystem. The electronic system includes a voltage regulator according toone or more embodiments disclosed herein, and a target load systemcoupled to the voltage regulator, wherein the output terminal of thestep-down regulator in the voltage regulator is coupled to the targetload system.

In one or more embodiments disclosed herein, the target load systemincludes a battery and the voltage regulator is configured to receivethe first voltage signal from a power line of a Universal Serial Bus andto provide the final voltage signal to the battery.

In one or more embodiments disclosed herein, the target load systemcomprises a System on Chip (SoC), and the SoC and the voltage regulatorare packaged in a single SoC package.

In one or more embodiments disclosed herein, the target load systemcomprises a System on Chip (SoC), and the SoC and the voltage regulatorare provided on a printed circuit board (PCB).

Some embodiments of the disclosed subject matter include an electronicsystem. The electronic system includes a voltage regulator according toone or more embodiments disclosed herein. The voltage regulator isconfigured to operate in a reverse direction in which the outputterminal of the step-down regulator in the voltage regulator is coupledto an input voltage source and the first input terminal of theswitched-inductor regulator is coupled to a target load of the voltageregulator.

In one or more embodiments disclosed herein, the electronic systemoperating the voltage regulator in a reverse direction is configured tooperate the voltage regulator as a step-up regulator.

In one or more embodiments disclosed herein, the output terminal of thestep-down regulator is coupled to a battery and the input terminal ofthe switched-inductor regulator is coupled to a power line of aUniversal Serial Bus.

BRIEF DESCRIPTION OF THE DRAWINGS

Various objects, features, and advantages of the disclosed subjectmatter can be more fully appreciated with reference to the followingdetailed description of the disclosed subject matter when considered inconnection with the following drawings, in which like reference numeralsidentify like elements.

FIGS. 1A-1B illustrate a buck regulator and its operation.

FIG. 2 shows a 3:1 step-down Dickson Star SC regulator.

FIGS. 3A-3C illustrate an operation of a 3:1 step-down Dickson Star SCregulator.

FIG. 4 illustrates an exemplary reconfigurable Dickson Star SC regulatorthat can be reconfigured to support a plurality of conversion ratios inaccordance with some embodiments.

FIGS. 5A-5C illustrate an operation of the reconfigurable regulator inFIG. 4 for the conversion ratio of 3:1 in accordance with someembodiments.

FIGS. 6A-6C illustrate an operation of the reconfigurable regulator inFIG. 4 for the conversion ratio of 2:1 in accordance with someembodiments.

FIGS. 7A-7C illustrate an operation of the reconfigurable regulator inFIG. 4 for the conversion ratio of 1:1 in accordance with someembodiments.

FIG. 8 illustrates a fixed conversion ratio 4:1 Dickson Star SCregulator.

FIGS. 9A-9C show an operation of the 4:1 Dickson Star SC regulator.

FIG. 10 shows a 4:1 reconfigurable Dickson Star SC regulator inaccordance with some embodiments.

FIGS. 11A-11C illustrate the operation of a 4:1 reconfigurable DicksonStar SC regulator in a 4:1 conversion mode in accordance with someembodiments.

FIGS. 12A-12C illustrate the operation of a 4:1 reconfigurable DicksonStar SC regulator in a 3:1 conversion mode in accordance with someembodiments.

FIGS. 13A-13C illustrate the operation of a 4:1 reconfigurable DicksonStar SC regulator in a 2:1 conversion mode in accordance with someembodiments.

FIGS. 14A-14C illustrate the operation of a 4:1 reconfigurable DicksonStar SC regulator in a 1:1 conversion mode in accordance with someembodiments.

FIGS. 15A-15B illustrate a N:1 reconfigurable Dickson Star SC regulatorin accordance with some embodiments.

FIG. 16 illustrates a 4:1 reconfigurable Dickson Star SC regulator inaccordance with some embodiments.

FIGS. 17A-17C illustrate the operation of a 4:1 reconfigurable DicksonStar SC regulator in a 4:1 conversion mode in accordance with someembodiments.

FIGS. 18A-18C illustrate the operation of a 4:1 reconfigurable DicksonStar SC regulator in a 3:1 conversion mode in accordance with someembodiments.

FIGS. 19A-19C illustrate the operation of a 4:1 reconfigurable DicksonStar SC regulator in a 2:1 conversion mode in accordance with someembodiments.

FIGS. 20A-20C illustrate the operation of a 4:1 reconfigurable DicksonStar SC regulator in a 1:1 conversion mode in accordance with someembodiments.

FIGS. 21A-21B illustrate a N:1 reconfigurable Dickson Star SC regulatorin accordance with some embodiments.

FIGS. 22-24 illustrate step-up reconfigurable Dickson-Star SC regulatorsin accordance with some embodiments.

FIG. 25 illustrates a two-stage voltage regulation system in which a SCregulator provides the first stage voltage regulation in accordance withsome embodiments.

FIGS. 26A-26B illustrate an embodiment of FIG. 25 in which the secondstage regulator is a buck converter in accordance with some embodiments.

FIG. 27 illustrates a two-stage voltage regulation system in which a SCregulator provides the second stage voltage regulation in accordancewith some embodiments.

FIGS. 28A-28B illustrate a two-stage voltage regulator in which thefirst stage regulator consists sole of an inductor in accordance withsome embodiments.

FIGS. 29A-29B illustrate an operation of a two-stage regulator in FIG.28 in which the SC regulator is a 4:1 Dickson Star switched-capacitor(SC) regulator in accordance with some embodiments.

FIG. 30 illustrates the duty-cycling of the second stage regulator andthe voltage swing of V_(TMP) in accordance with some embodiments.

FIG. 31 illustrates a two-stage voltage regulation system in which thesecond stage regulator is a multi-phase voltage regulator in accordancewith some embodiments.

FIG. 32 illustrates the phase relationship between switch capacitors inFIG. 31 in accordance with some embodiments.

FIG. 33 illustrates a control sequence of switches that allowsmaintaining the duty cycle of the first stage regulator in accordancewith some embodiments.

FIG. 34 is a block diagram of a computing device that includes a voltageregulation system in accordance with some embodiments.

FIGS. 35A-35C show an operation of a N:1 step-down Dickson Star SCregulator in the N:1 conversion mode.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forthregarding the apparatuses, systems, and methods of the disclosed subjectmatter and the environment in which such apparatuses, systems, andmethods may operate, etc., in order to provide a thorough understandingof the disclosed subject matter. It will be apparent to one skilled inthe art, however, that the disclosed subject matter may be practicedwithout such specific details, and that certain features, which are wellknown in the art, are not described in detail in order to avoidcomplication of the disclosed subject matter. In addition, it will beunderstood that the examples provided below are exemplary, and that itis contemplated that there are other apparatuses, systems, and methodsthat are within the scope of the disclosed subject matter.

Modern electronic systems have been tightly integrated as asystem-on-chip (SoC) that incorporates multiple processing cores andheterogeneous components (e.g., memory controllers, hardwareaccelerators) within a single chip. The popularity of SoCs, coupled withtighter power budgets, motivates controlling the voltage and frequencyat a block-specific granularity. The block-specific voltage control canallow the electronic system to raise only the voltage of the core(s)that desires higher performance. Such a block-specific voltage controlcan improve power and/or performance.

However, traditional approaches of dynamic voltage and frequency scaling(DVFS) have been performed at a coarse-grain level due to cost and sizelimitations of off-chip voltage regulators. Moreover, traditional DVFSschemes were limited to a slow voltage/frequency scaling at themicro-second timescale due to the slow speed of off-chip voltageregulators. Faster DVFS in nano-second timescale can save significantlymore power consumed by the SoC by closely tracking the SoC voltage tothe rapidly changing computation demand.

Given these drawbacks of off-chip voltage regulators, there has been asurge of interest in building integrated voltage regulators (IVR) toreduce board size and enable nanosecond timescale, per-core DVFS. An IVRcan include a variety of voltage regulators, including a switchingregulator and a low-dropout linear regulator. IVRs that can reduce theboard size and can enable nanosecond timescale, per-core DVFS aredisclosed in articles authored by inventors of the present application,including an article entitled “System Level Analysis of Fast, Per-CoreDVFS using On-Chip Switching Regulators,” published in IEEEInternational Symposium on High-Performance Computer Architecture (HPCA)in February 2008, by Wonyoung Kim et al.; an article entitled “DesignTechniques for Fully Integrated Switched-Capacitor DC-DC Converters,”published in IEEE Journal of Solid-State Circuits (JSSC) in September2011, by Hanh-Phuc Le et al.; and an article entitled “AFully-Integrated 3-Level DC/DC Converter for Nanosecond-Scale DVFS,”published in IEEE Journal of Solid-State Circuits (JSSC) in January2012, by Wonyoung Kim et al., each of which is hereby incorporatedherein by reference in its entirety.

A switching regulator can include a buck regulator. FIGS. 1A-1Billustrate a buck regulator and its operation. As illustrated in FIG.1A, the buck regulator 100 can include an inductor 108 and two switches114, 116. The buck regulator 100 can connect the inductor 108 to a firstvoltage source V_(IN) 104 and a second voltage source 118 through a setof power switches 114, 116. In some cases, the second voltage source 118can include a ground voltage source. The power switches 114, 116 can beturned on and off using external inputs. In some cases, the powerswitches 114, 116, can be controlled so that the two switches are notturned on at the same time. The power switches 114, 116 can includetransistors. The transistors can include a MOSFET transistor. Forexample, the switch 114 can include a P-channel MOSFET transistor; theswitch 116 can include an N-channel MOSFET transistor.

As illustrated in FIG. 1B, as the power switches 114, 116 turn on andoff with a period T, the input of the inductor V_(X) 102 can swingbetween 0 and V_(IN) with a period T. The inductor 108 and capacitor 120operate as a low-pass filter that averages V_(X) 102 over time, therebycreating a signal at the regulator output V_(OUT) 110 with a smallvoltage ripple. The output voltage V_(OUT) 110 can depend on the amountof time the inductor 108 is coupled to the first voltage source V_(IN)104 and the amount of time the inductor 108 is coupled to the secondvoltage source 118. For example, the buck regulator 100 can adjust thelevel of V_(OUT) 510 to V_(IN)D+(0V)(1−D), where D, a number between 0and 1, is the portion of time V_(X) is coupled to V_(IN). D is alsoreferred to as a duty cycle. The output load that consumes the current106 can be any type of an electronic device, including processors,memory (DRAM, NAND flash), RF chips, WiFi combo chips, and poweramplifiers.

The efficiency of the buck regulator 100 can be computed as:

$\eta = \frac{P_{L}}{P_{O}}$where P_(L) indicates the power delivered to the output load 106 andP_(O) indicates the output power of the buck regulator 108. P_(L) can becomputed as follows: P_(L)=P_(O)−P_(LOSS), where P_(LOSS) includes theamount of power losses during the voltage regulation process.

One of the major power losses P_(LOSS) associated with a buck regulator100 includes a resistive loss P_(R) incurred by the parasitic resistanceof the inductor 108. When the buck regulator 100 delivers power to theoutput load 106 by providing current 112, ideally, the buck regulator100 provides all of its output power to the output load 106. However, ina practical scenario, the buck regulator 100 dissipates some of itsoutput power internally at the inductor 108. Ideally, an inductor 108has zero resistance. Therefore, a current through the inductor 108 wouldnot dissipate any power. However, in a practical scenario, an inductor108 is associated with a finite resistance, primarily due to theresistance of the material forming the inductor 108. This undesirable,finite resistance of the inductor 108 is referred to as a parasiticresistance. The parasitic resistance can incur a resistive power losssince the parasitic resistance can cause the current through theinductor 108 to dissipate energy. Therefore, the resistive power losscan reduce the power conversion efficiency of the buck regulator 100.

When the current is alternating, then the resistive power loss can becomputed as P_(R)=I_(L,RMS) ²R_(L), where R_(L) is the value of theparasitic resistance of the inductor 108, and I_(L,RMS) is the root-meansquare of the current through the inductor 108. I_(L,RMS) can be reducedby reducing the peak-to-peak ripple of the inductor current (I_(L,PP)120). Therefore, the buck regulator 100 can reduce the resistive lossP_(R) by reducing the peak-to-peak ripple of the inductor currentI_(L,PP) 120.

There are two ways to reduce the peak-to-peak ripple of the inductorcurrent I_(L,PP) 120. First, the buck regulator 100 can switch at a highfrequency and reduce the period of the switching regulator T. However,this solution can increase the power consumed to charge and dischargethe parasitic capacitance at the junction 208 between switches 114, 116.This capacitive power loss can be significant because the size of theswitches 114, 116 can be large, which increases the parasiticcapacitance, and because the voltage swing on V_(X) 202 is large. Thiscapacitive power loss can be computed as follows: P_(C)=fCV², where C isthe amount of the parasitic capacitance at the junction 208, f is thefrequency at which the buck regulator 100 switches, and V is the voltageswing at the junction 208. This power loss can be significant becausethe size of the switches 114, 116 is large, which increases theparasitic capacitance, and because the voltage swing on V_(X) 202 islarge.

Second, the buck regulator 100 can use an inductor 108 with a highinductance value, thereby reducing the parasitic resistance R_(L).However, this approach makes the inductor 108 large and makesintegration difficult.

A switching regulator can also include a switched-capacitor (SC)regulator. An SC regulator can use one or more capacitors, instead ofinductors, to transfer charges from a power source to an output load. AnSC regulator can use power switches to connect/disconnect one or morecapacitors to one of multiple voltages, thereby providing an outputvoltage that is a weighted average of the multiple voltages. The SCregulator can control the output voltage by changing the configurationand the sequence in which capacitors are coupled to one another. Becausecapacitors are easier to integrate on-die or on-package than inductors,it is easier to implement SC IVRs with a small size.

One type of a SC regulator is a Dickson Star SC regulator. An example ofa 3:1 step-down Dickson Star SC regulator (a step-down Dickson Star SCregulator that is configured to divide an input voltage level by 1/3) isillustrated in FIG. 2. The Dickson Star SC regulator has severaladvantages compared to other SC regulator topologies. First, it usesfewer capacitors compared to other SC regulator topologies, such as aladder type SC regulator. Second, it can use, as switches, transistorswith lower voltage ratings compared to other SC regulator topologies,such as a series to parallel SC regulator. Third, it can be more easilyscaled to higher input voltages compared to other SC regulatortopologies, such as a series to parallel SC regulator.

A Dickson Star SC regulator 200 can include switching capacitors C1_(FLY) 204 and C2 _(FLY) 206, and a switch matrix including a pluralityof switches 216-228 configured to electrically couple the switchingcapacitors C1 _(FLY) 204 and C2 _(FLY) 206 to an input voltage nodeV_(IN) 202, an output voltage node V_(OUT) 208, and a ground node GND210. The output node V_(OUT) 208 is coupled to an output load I_(OUT)212 and a decoupling capacitor C_(OUT) 214.

FIGS. 3A-3C illustrate the basic operation of the Dickson Star SCregulator 200. As shown in FIG. 3C, the Dickson Star SC regulator 200 isduty-cycled between State0 (illustrated in FIG. 3A) and State 1(illustrated in FIG. 3B) over time with a duty cycle D. The value of theduty cycle (D) can be any value between 0 and 1, and preferably between0.25 and 0.75.

When the switching capacitors C1 _(FLY) 204 and C2 _(FLY) 206 are largeenough, the voltages across these switching capacitors, V_(C1FLY),V_(C2FLY), respectively, stay roughly constant between State0 and State1. Additionally, the decoupling capacitor C_(OUT) 214, which is oftenlarge, is always coupled to the output V_(OUT) 208 to reduce noise onthe output. Therefore, the output voltage V_(OUT) 208 stays roughlyconstant in State0 and State1. Based on these characteristics, thefollowing voltage relationships can be derived:State0: V _(OUT) 208+V _(C1FLY) =V _(C2FLY)State1: V _(OUT) 208=V _(C1FLY)State1: V _(OUT) 208+V _(C2FLY) =V _(IN) 202By eliminating V_(C1FLY) and V_(C2FLY) from these relationships, thefollowing relationship can be derived:V _(OUT)=(1/3)×V _(IN)

This shows that alternating between State0 and State1 provides a 3:1step-down voltage regulation. This 3:1 step-down Dickson Star SCregulator design can be extended to a N:1 step-down Dickson Star SCregulator, where N is a number greater than 3.

FIGS. 35A-35B show the topology and operation of a N:1 step-down DicksonStar SC regulator. The N:1 step-down Dickson Star SC regulator caninclude a capacitor matrix (also referred to as a capacitor bank). Thecapacitor matrix can include a first capacitor sub-matrix and a secondcapacitor sub-matrix. The capacitors in the first capacitor sub-matrixare referred to as C(1, j), where the first index “1” refers to the“first” capacitor matrix, and the second index “j” refers to the j^(th)capacitor in the first capacitor sub-matrix. Likewise, the capacitors inthe second capacitor sub-matrix are referred to as C(2, j). In FIGS.4A-4B, the first capacitor sub-matrix include M number of capacitors;and the second capacitor sub-matrix include K number of capacitors. Mcan be equal to floor(N/2), and K can be equal to floor ((N−1)/2).

The N:1 step-down Dickson-Star SC regulator includes a plurality ofswitch matrices. The switches in the first switch sub-matrix include thebottom four switches SW1 216, SW2 218, SW3 220, SW4 222. The switches inthe second switch sub-matrix are referred to as SW(2, j), where theindex “j” refers to the j^(th) switch in the switch matrix.

In FIGS. 35A-35B, the number of switches and connections of the switchesin the first switch sub-matrix SW1 216, SW2 218, SW3 220, SW4 222 do notchange regardless of the value of “N”. The second switch sub-matrixincludes F number of switches, and the value F can be equal to M+K+1.

SW1 216 is connected to V_(OUT) 208 and one terminal of SW2 218. SW2 218is connected to V_(OUT) 208 and one terminal of SW4 222. All switches inthe second switch sub-matrix are connected in series. For example, SW(2,j) is connected to one terminal of C(1,p) and C(2, q). The value p canbe equal to ceiling(j/2) and the value q can be equal to floor(j/2). SW1216 and SW2 218 are connected to the other terminal of C(1,p), while SW3220 and SW4 222 are connected to the other terminal of C(1,q).

The N:1 step-down Dickson-Star SC regulator can be duty-cycled betweenState0 and State 1, shown in FIG. 35A and FIG. 35B, respectively, byturning on and off switches in the switch matrices.

FIGS. 35A-35B show the operation of the N:1 step-down Dickson Star SCregulator in the N:1 conversion mode. In State0, in the first switchsub-matrix, SW1 216 and SW3 220 are turned off, while SW2 218 and SW4222 are turned on. In the second switch sub-matrix, all odd indexedswitches are off while all even indexed switches are on. Subsequently,in State1, all switch states are inverted compared to State0.

An advantage of this switch configuration is that all switches only haveat most V_(OUT) 208 applied across them, regardless of how large N is.One drawback is that some capacitors have high voltages applied acrossthem, which requires high voltage rated capacitors that can be bulky andexpensive. In some embodiments, the voltages across the capacitorsV_(C(1,p)) and V_(C(2,q)) are equal to ((p−1)×2+1)×V_(OUT) 208 andq×2×V_(OUT) 208. As a result, this Dickson Star configuration is usefulwhen low voltage switches and high voltage capacitors are available.

Although Dickson Star SC regulators can be useful, such a design wouldstill be limited to a single conversion ratio (a ratio between an inputvoltage V_(IN) 202 and an output voltage V_(OUT) 208 of N:1 and cannotefficiently regulate voltages to provide other conversion ratios.

One disadvantage of using a single-conversion ratio SC regulator is thelimited range of output voltages. Oftentimes, efficiencies of SCregulators can degrade at output voltages that are not a predeterminedfraction (e.g., 1/N) of the input voltage. As discussed with respect toFIGS. 3A-3C, an SC regulator is typically optimized to achieve highefficiency at a single conversion ratio. For example, when a SCregulator is coupled to a battery providing 3.3V, the SC regulator maybe optimized to receive the 3.3V and provide a fixed output voltage of1.1V. In this case, the efficiency of the SC regulator is optimized toprovide an output voltage of 1.1V—the efficiency of the SC regulatorwould degrade as the output voltage deviates from 1.1V. Put another way,the SC regulator may be optimized to provide a high efficiency at aconversion ratio of 3:1, and the efficiency of the SC regulator maydegrade as the conversion ratio deviates from 3:1. This efficiencydegradation is unfortunate because a system on chip (SoC) may operate atmany voltage levels, and it would be desirable to use a single SCregulator to accommodate all of those voltage levels in the SoC.

One way to support multiple conversion ratios is to provide a pluralityof regulators each dedicated to a particular conversion ratio, andenable only one of these regulators depending on which conversion rationeeds to be supported. However, this requires many redundant capacitorsand switches. For example, when the 3:1 regulator is being used, allswitches and capacitors for 2:1 and 1:1 regulators stay idle withoutbeing used. The redundant capacitors and switches require real estate onan integrated circuit chip and add costs, both of which are undesirable.

Therefore, it would be desirable to provide a single SC regulator thatcould achieve high efficiencies at multiple conversion ratios. In otherwords, it would be desirable to provide a single SC regulator that couldbe reconfigured for one of many conversion ratios (e.g., 1/2, 1/3, 2/3,2/5, 3/5, 4/5) so that a single SC regulator can accommodate one of manyoutput voltage levels at high efficiency.

The present disclosure shows a reconfigurable Dickson Star SC regulatorthat can support multiple conversion ratios by reconfiguring betweenvarious modes. The reconfigurable Dickson Star SC regulator is designedto reduce the number of redundant capacitors by reusing capacitors andswitches across multiple modes of operation (across multiple conversionratios).

In some embodiments, a reconfigurable Dickson Star SC regulator includesa regular Dickson Star SC regulator and a mode switch matrix. The modeswitch matrix includes a plurality of switches coupled to the regularDickson Star SC regulator. Depending on the desired conversion ratio,one or more switches in the mode switch matrix may be enabled toreconfigure the arrangement of capacitors in the regular Dickson Star SCregulator. This way, the mode switch matrix is capable of reconfiguringthe conversion ratio of the regular fixed-conversion mode Dickson StarSC regulator.

In some embodiments, depending on the reconfigured conversion ratio ofthe reconfigurable Dickson Star SC regulator, switches in the regularfixed-conversion mode Dickson Star SC regulator may be controlleddifferently (compared to its regular fixed-conversion mode operation) toaccount for the reconfigured arrangement of capacitors.

In the foregoing discussions, a N:1 reconfigurable Dickson Star SCregulator refers to a reconfigurable Dickson Star SC regulator that canbe reconfigured to provide any one of M:1 conversion ratios, where M isa value between 1 and N.

FIG. 4 illustrates an exemplary reconfigurable Dickson Star SC regulatorthat can be reconfigured to support a plurality of conversion ratios inaccordance with some embodiments. FIG. 4 shows a 3:1 reconfigurableDickson Star SC regulator 400 that can be reconfigured into one ofconversion ratios: 3:1, 2:1, 1:1. The 3:1 reconfigurable Dickson Star SCregulator 400 includes a fixed 3:1 Dickson Star SC regulator 200 of FIG.2, identified using the box 404, and a mode switch matrix 406 includinga single mode switch SW8 402. This additional mode switch 402 can beselectively operated to transform a fixed 3:1 Dickson Star SC regulatorof FIG. 2 into a 3:1 reconfigurable Dickson Star SC regulator.

FIGS. 5-7 illustrate the operation of the reconfigurable regulator inFIG. 4 for conversion ratios 3:1, 2:1, 1:1, respectively, in accordancewith some embodiments. As shown in FIGS. 5A-5C, to operate thereconfigurable Dickson Star SC regulator 400 in a 3:1 conversion mode,the mode switch SW8 402 can be simply turned off (in an “open”position), and the fixed 3:1 Dickson Star SC regulator 404 in thereconfigurable regulator 400 can be operated the same way as in FIG. 3(a plurality of switches can be duty-cycled to switch the regulatorbetween State0 and State1).

As shown in FIGS. 6A-6C, to operate the reconfigurable Dickson Star SCregulator 400 in a 2:1 conversion mode, as the fixed 3:1 regulator 404is duty-cycled between State0 and State1, the switch SW8 402 can beturned on during State0 and the switch SW8 402 can be turned off duringState 1. In some sense, this 3:1 reconfigurable Dickson Star SCregulator operates in a 2:1 conversion mode because the mode switch SW8402 ties together all switching capacitors C1 _(FLY) 204, C2 _(FLY) 206in a parallel manner and makes them to operate collectively as a singlelarge capacitor in State0, just as in a traditional 2:1 SC regulator.For example, in a traditional 2:1 SC regulator, a switching capacitor,or several switching capacitors connected in parallel acting like oneswitching capacitor, is connected between the input and output voltagesin one state, while it is connected between the output voltage andground in another state. By switching between these two states, theoutput voltage becomes half of the input voltage. The switches in FIGS.6A-6B are turned on and off accordingly so that the switching capacitorsbehave like as in a traditional 2:1 SC regulator.

As shown in FIGS. 7A-7C, to operate the reconfigurable Dickson Star SCregulator 400 in a 1:1 conversion mode, as the regulator is duty-cycledbetween State0 and State1, the switch SW8 402 can be turned on duringState0 and the switch SW8 402 can be turned off during State 1. Theremaining switches are turned on and off accordingly so that theswitching capacitors behave like as in a traditional 1:1 SC regulator.For example, in a traditional 1:1 SC regulator, a switching capacitor,or several switching capacitors connected in parallel acting like oneswitching capacitor, is connected between the input voltage and groundin one state, while it is connected between the output voltage andground in another state. By switching between these two states, theoutput voltage becomes similar to the input voltage. The switches inFIGS. 7A-7B are turned on and off accordingly so that the switchingcapacitors behave like as in a traditional 1:1 SC regulator.

In some embodiments, the reconfigurable Dickson Star SC regulator can bea 4:1 reconfigurable Dickson Star SC regulator. In other words, thereconfigurable Dickson Star SC regulator can be configured to provideone of the following conversion ratios: 4:1, 3:1, 2:1, 3:1. Tofacilitate the discussion of the 4:1 reconfigurable Dickson Star SCregulator, FIG. 8 illustrates a fixed conversion ratio 4:1 Dickson StarSC regulator 800. Compared to the 3:1 Dickson Star SC regulator 200 inFIG. 2, the 4:1 Dickson Star SC regulator 800 has one more switchingcapacitor C3 _(FLY) 802 and one more switch SW9 804.

Similar to the 3:1 Dickson Star SC regulator 200, the 4:1 regulator 800is duty-cycled between State0 and State1 to provide voltage regulation.FIGS. 9A-9C show the duty-cycling of the 4:1 regulator 800 betweenState0 and State1. Assuming that the switching capacitors C1 _(FLY) 204,C2 _(FLY) 206, and C3 _(FLY) 802 and the decoupling capacitor C_(OUT)214 are large, the following relationships can be derived for the twostates:State0: V _(IN) 202=V _(C3FLY) +V _(OUT) 208State0: V _(C2FLY) =V _(C1FLY) +V _(OUT) 208State1: V _(OUT) 208=V _(C1FLY)State1: V _(C3FLY) =V _(OUT) 208+V _(C2FLY)where V_(C1FLY) is a voltage across the first switching capacitor C1_(FLY) 204, V_(C2FLY) is a voltage across the second switching capacitorC2 _(FLY) 206, and V_(C1FLY) is a voltage across the third switchingcapacitor C3 _(FLY) 802. These relationship can be reorganized asfollows:V _(C2FLY)=2×V _(OUT)V _(C3FLY)=3×V _(OUT)V _(OUT)=(1/4)×V _(IN)Therefore, the Dickson Star SC regulator illustrated in FIG. 8 operatesas a 4:1 step-down Dickson Star SC regulator.

In some embodiments, the fixed conversion mode 4:1 Dickson Star SCregulator can be augmented with a mode switch matrix to provide a 4:1reconfigurable Dickson Star SC regulator. FIG. 10 shows a 4:1reconfigurable Dickson Star SC regulator in accordance with someembodiments. The 4:1 reconfigurable Dickson Star SC regulator 1000includes a fixed conversion mode 4:1 Dickson Star SC regulator and amode switch matrix with two mode switches SW10 1002 and SW11 1004. Themode switch matrix is designed to reconfigure the arrangement ofcapacitors in the fixed conversion mode 4:1 Dickson Star SC regulator800 to enable reconfiguration between 4:1, 3:1, 2:1, 1:1 conversionratios.

FIGS. 11A-11C illustrate the operation of a 4:1 reconfigurable DicksonStar SC regulator in a 4:1 conversion mode in accordance with someembodiments. In this mode of operation, while the Dickson Star SCregulator duty-cycles between State0 and State1 as shown in FIG. 11C,the mode switches SW10 1002 and SW11 1004 are also duty-cycled toprovide a 4:1 conversion ratio, behaving similarly as SW1 216 and SW2218. For example, in State0, the first mode switch SW10 1002 is turnedoff (“open”) and the second mode switch SW11 1004 is turned on(“closed”), and in State1, the first mode switch SW10 1002 is turned on(“closed”) and the second mode switch SW11 1004 is turned off (“open”).

Assuming that the switching capacitors C1 _(FLY) 204, C2 _(FLY) 206, andC3 _(FLY) 802 and the decoupling capacitor C_(OUT) 214 are large, thefollowing relationships can be derived for the two states:State0: V _(IN) 202=V _(C3FLY) +V _(OUT) 208State0: V _(C2FLY) =V _(C1FLY) +V _(OUT) 208State1: V _(OUT) 208=V _(C1FLY)State1: V _(C3FLY) =V _(OUT) 208+V _(C2FLY)where V_(C1FLY) is a voltage across the first switching capacitor C1_(FLY) 204, V_(C2FLY) is a voltage across the second switching capacitorC2 _(FLY) 206, and V_(C1FLY) is a voltage across the third switchingcapacitor C3 _(FLY) 802. These relationships can be reorganized asfollows:V _(C2FLY)=2×V _(OUT)V _(C3FLY)=3×V _(OUT)V _(OUT)=(1/4)×V _(IN)Therefore, the reconfigurable Dickson Star SC regulator illustrated inFIGS. 11A-11B operates as a 4:1 step-down Dickson Star SC regulator.

FIGS. 12A-12C illustrate the operation of a 4:1 reconfigurable DicksonStar SC regulator in a 3:1 conversion mode in accordance with someembodiments. In this mode of operation, while the regulator duty-cyclesbetween State0 and State1 as shown in FIG. 12C, the mode switches SW101002 and SW11 1004 are also duty-cycled to provide a 3:1 conversionratio. For example, in State0, the first mode switch SW10 1002 is turnedon (“closed”) and the second mode switch SW11 1004 is turned off(“open”), and in State1, the first mode switch SW10 1002 is turned off(“open”) and the second mode switch SW11 1004 is turned on (“closed”).

In some sense, the operation of this 4:1 reconfigurable Dickson Star SCregulator operating in the 3:1 conversion mode is similar to theoperation of the fixed conversion mode 3:1 Dickson Star SC regulator 200in FIG. 2. For example, the switching capacitors C2 _(FLY) 206 and C3_(FLY) 802 are tied together in parallel to provide a larger singlecapacitor, which together operates as C2 _(FLY) 206 in FIG. 2. Asanother example, the switching capacitor C1 _(FLY) 204 in FIGS. 12A-12Boperates as C1 _(FLY) 204 in FIG. 2. Therefore, although the number ofcapacitors in the 4:1 reconfigurable Dickson Star SC regulator isdifferent from the fixed conversion mode 3:1 Dickson Star SC regulatorin FIG. 2, the 4:1 reconfigurable Dickson Star SC regulator can operatein the 3:1 conversion mode through reconfiguration of capacitorarrangements using a plurality of switches.

Assuming that the switching capacitors C1 _(FLY) 204, C2 _(FLY) 206, andC3 _(FLY) 802 and the decoupling capacitor C_(OUT) 214 are large, thefollowing relationships can be derived for the two states:State0: V _(C2FLY) =V _(C3FLY)State0: V _(C2FLY) =V _(C1FLY) +V _(OUT) 208State1: V _(OUT) 208=V _(C1FLY)State1: V _(IN) 202=V _(OUT) 208+V _(C2FLY)where V_(C1FLY) is a voltage across the first switching capacitor C1_(FLY) 204, V_(C2FLY) is a voltage across the second switching capacitorC2 _(FLY) 206, and V_(C1FLY) is a voltage across the third switchingcapacitor C3 _(FLY) 802. These relationships can be reorganized asfollows:V _(C2FLY)=2×V _(OUT) 208V _(C3FLY)=2×V _(OUT) 208V _(OUT)=(1/3)×V _(IN)Therefore, the reconfigurable Dickson Star SC regulator illustrated inFIGS. 12A-12C operates as a 3:1 step-down Dickson Star SC regulator.

FIGS. 13A-13C illustrate the operation of a 4:1 reconfigurable DicksonStar SC regulator in a 2:1 conversion mode in accordance with someembodiments. In this mode of operation, while the Dickson Star SCregulator duty-cycles between State0 and State1 as shown in FIG. 13C,the mode switches SW10 1002 and SW11 1004 are also duty-cycled toprovide a 2:1 conversion ratio. For example, in State0, the first modeswitch SW10 1002 is turned off (“open”) and the second mode switch SW111004 is turned on (“closed”), and in State 1, the first mode switch SW101002 is turned on (“closed”) and the second mode switch SW11 1004 isturned off (“open”).

In some sense, this 4:1 reconfigurable Dickson Star SC regulatoroperates in a 2:1 conversion mode because the regulator ties togetherall three switching capacitors C1 _(FLY) 204, C2 _(FLY) 206, C3 _(FLY)802 in parallel and makes them to operate collectively as a single largecapacitor, just as in a traditional 2:1 SC regulator. For example, in atraditional 2:1 SC regulator, a switching capacitor, or severalswitching capacitors connected in parallel acting like one switchingcapacitor, is connected between the input and output voltages in onestate, while it is connected between the output voltage and ground inanother state. By switching between these two states, the output voltagebecomes half of the input voltage. The switches in FIGS. 13A-13B areturned on and off accordingly so that the switching capacitors behavelike as in a traditional 2:1 SC regulator.

Assuming that the switching capacitors C1 _(FLY) 204, C2 _(FLY) 206, andC3 _(FLY) 802 and the decoupling capacitor C_(OUT) 214 are large, thefollowing relationships can be derived for the two states:State0: V _(C1FLY) =V _(C2FLY) =V _(C3FLY) =V _(IN) 202−V _(OUT) 208State1: V _(C1FLY) =V _(C2FLY) =V _(C3FLY) =V _(OUT) 208where V_(C1FLY) is a voltage across the first switching capacitor C1_(FLY) 204, V_(C2FLY) is a voltage across the second switching capacitorC2 _(FLY) 206, and V_(C1FLY) is a voltage across the third switchingcapacitor C3 _(FLY) 802. These relationships can be reorganized asfollows:V _(C1FLY) =V _(OUT)V _(C2FLY) =V _(OUT)V _(C3FLY) =V _(OUT)V _(OUT)=(1/2)×V _(IN)Therefore, the reconfigurable Dickson Star SC regulator illustrated inFIGS. 13A-13C operates as a 2:1 step-down Dickson Star SC regulator.

FIGS. 14A-14C illustrate the operation of a 4:1 reconfigurable DicksonStar SC regulator in a 1:1 conversion mode in accordance with someembodiments. In this mode of operation, while the Dickson Star SCregulator duty-cycles between State0 and State1 as shown in FIG. 14C,the mode switches SW10 1002 and SW11 1004 are not duty-cycled. Forexample, in both State0 and State1, the first mode switch SW10 1002 isturned on (“closed”) and the second mode switch SW11 1004 is turned off(“open”).

In some sense, this 4:1 reconfigurable Dickson Star SC regulatoroperates in a 1:1 conversion mode because the regulator ties togetherall three switching capacitors C1 _(FLY) 204, C2 _(FLY) 206, C3 _(FLY)802 in parallel and makes them to operate collectively as a single largecapacitor, just as in a traditional 1:1 SC regulator. For example, in atraditional 1:1 SC regulator, a switching capacitor, or severalswitching capacitors connected in parallel acting like one switchingcapacitor, is connected between the input voltage and ground in onestate, while it is connected between the output voltage and ground inanother state. By switching between these two states, the output voltagebecomes similar to the input voltage. The switches in FIGS. 14A-14B areturned on and off accordingly so that the switching capacitors behavelike as in a traditional 1:1 SC regulator.

Assuming that the switching capacitors C1 _(FLY) 204, C2 _(FLY) 206, andC3 _(FLY) 802 and the decoupling capacitor C_(OUT) 214 are large, thefollowing relationships can be derived for the two states:State0: V _(C1FLY) =V _(C2FLY) =V _(C3FLY) =V _(IN) 202State1: V _(C1FLY) =V _(C2FLY) =V _(C3FLY) =V _(OUT) 208where V_(C1FLY) is a voltage across the first switching capacitor C1_(FLY) 204, V_(C2FLY) is a voltage across the second switching capacitorC2 _(FLY) 206, and V_(C1FLY) is a voltage across the third switchingcapacitor C3 _(FLY) 802. These relationships can be reorganized asfollows:V _(C1FLY) =V _(OUT)V _(C2FLY) =V _(OUT)V _(C3FLY) =V _(OUT)V _(OUT) =V _(IN)Therefore, the reconfigurable Dickson Star SC regulator illustrated inFIGS. 14A-14C operates as a 1:1 step-down Dickson Star SC regulator.

In some embodiments, the 3:1 reconfigurable Dickson Star SC regulator400 illustrated in FIG. 4 and the 4:1 reconfigurable Dickson Star SCregulator 1000 illustrated in FIG. 10 can be extended to a N:1reconfigurable Dickson Star SC regulator, where N can be any numbergreater than one.

FIGS. 15A-15B illustrate a N:1 reconfigurable Dickson Star SC regulatorin accordance with some embodiments.

In some embodiments, the N:1 reconfigurable Dickson Star SC regulator1500 can include a capacitor matrix (also referred to as a capacitorbank). The capacitor matrix can include a first capacitor sub-matrix anda second capacitor sub-matrix. The capacitors in the first capacitorsub-matrix are referred to as C(1, j), where the first index “1” refersto the “first” capacitor matrix, and the second index “j” refers to thej^(th) capacitor in the first capacitor sub-matrix. Likewise, thecapacitors in the second capacitor sub-matrix are referred to as C(2,j). In FIGS. 15A-15B, the first capacitor sub-matrix include M number ofcapacitors; and the second capacitor sub-matrix include K number ofcapacitors. In some embodiments, M is equal to floor(N/2), and K isequal to floor((N−1)/2).

In some embodiments, the N:1 reconfigurable Dickson-Star SC regulator1500 includes a switch matrix having a first switch sub-matrix, a secondswitch sub-matrix, a third switch sub-matrix, a fourth switchsub-matrix, and a fifth switch matrix.

The switches in the first switch sub-matrix are referred to as SW(1, j),where the first index “1” refers to the “first” switch matrix, and thesecond index “j” refers to the j^(th) switch in the first switchsub-matrix. Likewise, the switches in the second switch sub-matrix arereferred to as SW(2, j); the switches in the third switch sub-matrix arereferred to as SW(3, j); the switches in the fourth switch sub-matrixare referred to as SW(4, j); and the switches in the fifth switchsub-matrix are referred to as SW(5, j).

In FIGS. 15A-15B, the first switch sub-matrix and second switchsub-matrix each includes M number of switches; the third switchsub-matrix and the fourth switch sub-matrix each includes K number ofswitches; and the fifth switch sub-matrix include L number of switches.In some embodiments, M is equal to floor(N/2); K is equal tofloor((N−1)/2); and L is equal to N.

In some embodiments, this regulator 1500 can be duty-cycled betweenState0 and State1 by turning on and off switches in the switch matrix ofthe regulator 1500.

FIGS. 15A-15B show the operation of the N:1 reconfigurable Dickson StarSC regulator 1500 in the N:1 conversion mode in accordance with someembodiments. In State0, all switches in the first switch sub-matrix atthe bottom left side are turned on, while all switches in the secondswitch sub-matrix side are turned off. Additionally, all switches in thethird switch sub-matrix are turned off while all switches in the fourthswitch sub-matrix are turned on. In the fifth switch sub-matrix, all oddindexed switches are off while all even indexed switches are on.Subsequently, in State1, all switch states are inverted compared toState0. While there are additional switches, including SW(j,1), SW(j,2),SW(j,3), SW(j,4) where j is larger than 1, the capacitor topologies aresimilar to the N:1 step-down Dickson Star in FIG. 35.

To operate the N:1 reconfigurable Dickson-Star SC regulator 1500 in the(N−1):1 conversion mode, the capacitor with the highest index in thefirst capacitor sub-matrix (C(1, M)) and the capacitor with the highestindex in the second capacitor sub-matrix (C(2, K)) can be tied togetherin parallel to operate as a single capacitor. This “single” capacitorcan work similar to C(1, M) in an (N−1):1 fixed conversion modeDickson-Star SC regulator—a Dickson-Star SC regulator that is identicalto a N:1 fixed conversion mode Dickson-Star SC regulator without C(2,K), which is the capacitor that is connected to V_(IN) 202 through fewerswitches, and the top switch in the 5th switch matrix, which is SW(5,L), and SW(3, K) and SW(4, K), which are two switches connected toC(2,K).

To operate the N:1 reconfigurable Dickson-Star SC regulator in the(N−2):1 conversion mode, three capacitors that are connected to V_(IN)202 through fewest switches (or, put differently) in the fifth switchsub-matrix can be tied together in parallel to work like a singlecapacitor. These three capacitors includes, for example, one capacitorwith the highest index in the first capacitor sub-matrix C(1, M) and twocapacitors with the highest indices in the second capacitor sub-matrix(C(2, K), C(2, K−1)). This “single” capacitor can work similar to C(2,K−1) in an (N−2):1 fixed conversion mode Dickson-Star SC regulator-aDickson-Star SC regulator that is identical to a N:1 fixed conversionmode Dickson-Star SC regulator without C(1, M) and C(2, K) and the toptwo switches in the 5th switch matrix, which are SW(5, L) and SW(5,L−1), and SW(1,M), SW(2,M), SW(3,K), SW(4,K), which are switchesconnected to C(1,M) and C(2,K).

More generally, to operate the N:1 reconfigurable Dickson-Star SCregulator in the (N−R):1 conversion mode, “R+1” number of capacitorsthat are connected to V_(IN) 202 through fewest switches in the fifthswitch sub-matrix can be tied together in parallel to work like a singlecapacitor, and operate the remaining switches as if operating the(N−R):1 fixed conversion mode Dickson-Star SC regulator.

In some embodiments, another topology of a Dickson Star SC regulator canenable reconfiguration between conversion modes. FIG. 16 illustrates a4:1 reconfigurable Dickson Star SC regulator in accordance with someembodiments. The 4:1 reconfigurable Dickson Star SC regulator 1000 inFIGS. 10-14 have two additional mode switches SW10 1002 and SW11 1004compared to a fixed conversion mode 4:1 Dickson Star SC regulator 800 inFIG. 8. FIG. 16 illustrates a different type of 4:1 reconfigurableDickson Star SC regulator, which uses two additional mode switches SW121602 and SW 13 1604 in different locations.

FIGS. 17A-17C illustrate the operation of a 4:1 reconfigurable DicksonStar SC regulator operating in the 4:1 conversion mode in accordancewith some embodiments. Although the locations of mode switches areslightly different, the capacitor topology in State0 and State1 is sameas the regulator 1000 in FIGS. 11A-11B. Therefore, the relationshipsbetween voltages across capacitors in State0 and State1 in FIGS. 17A-17Bare identical to the relationships between voltages across capacitors inState0 and State1 in FIGS. 11A-11B. As in FIGS. 11A-11B, assuming thatthe switching capacitors C1 _(FLY) 204, C2 _(FLY) 206, and C3 _(FLY) 802and the decoupling capacitor C_(OUT) 214 are large, the followingrelationships can be derived for the two states:State0: V _(IN) 202=V _(C3FLY) +V _(OUT) 208State0: V _(C2FLY) =V _(C1FLY) +V _(OUT) 208State1: V _(OUT) 208=V _(C1FLY)State1: V _(C3FLY) =V _(OUT) 208+V _(C2FLY)where V_(C1FLY) is a voltage across the first switching capacitor C1_(FLY) 204, V_(C2FLY) is a voltage across the second switching capacitorC2 _(FLY) 206, and V_(C1FLY) is a voltage across the third switchingcapacitor C3 _(FLY) 802. These relationship can be reorganized asfollows:V _(C2FLY)=2×V _(OUT)V _(C3FLY)=3×V _(OUT)V _(OUT)=(1/4)×V _(IN)Therefore, the reconfigurable Dickson Star SC regulator illustrated inFIGS. 17A-17B operates as a 4:1 step-down Dickson Star SC regulator.

FIGS. 18A-18C illustrate the operation of a 4:1 reconfigurable DicksonStar SC regulator in the 3:1 conversion mode in accordance with someembodiments. The operating principle in the 3:1 conversion mode issimilar to the 3:1 SC regulator illustrated in FIG. 2. The switchingcapacitors C1 _(FLY) 204 and C3 _(FLY) 802 are tied together in parallelto operate as a single large capacitor, similar to the capacitor C1_(FLY) 204 in FIG. 2. The switching capacitor C2 _(FLY) 206 in FIGS.18A-18B operates in a similar way as C2 _(FLY) 206 in FIG. 2.

Assuming that the switching capacitors C1 _(FLY) 204, C2 _(FLY) 206, andC3 _(FLY) 802 and the decoupling capacitor C_(OUT) 214 are large, thefollowing relationships can be derived for the two states:State0: V _(C2FLY) =V _(C3FLY)State0: V _(C2FLY) =V _(C1FLY) +V _(OUT) 208State1: V _(OUT) 208=V _(C1FLY)State1: V _(IN) 202=V _(OUT) 208+V _(C2FLY)where V_(C1FLY) is a voltage across the first switching capacitor C1_(FLY) 204, V_(C2FLY) is a voltage across the second switching capacitorC2 _(FLY) 206, and V_(C1FLY) is a voltage across the third switchingcapacitor C3 _(FLY) 802. These relationship can be reorganized asfollows:V _(C2FLY)=2×V _(OUT) 208V _(C3FLY)=2×V _(OUT) 208V _(OUT)=(1/3)×V _(IN)Therefore, the reconfigurable Dickson Star SC regulator illustrated inFIGS. 18A-18C operates as a 3:1 step-down Dickson Star SC regulator.

FIGS. 19A-19C illustrate the operation of a 4:1 reconfigurable DicksonStar SC regulator when it is working in 2:1 mode in accordance with someembodiments. The basic principle is similar to the 4:1 reconfigurableDickson Star SC regulator illustrated in FIGS. 13A-13B. The switchingcapacitors C1 _(FLY) 204, C2 _(FLY) 206, C3 _(FLY) 802 are tied inparallel to work like a single large capacitor, just like capacitors C1_(FLY) 204, C2 _(FLY) 206, C3 _(FLY) 802 were tied in parallel to worklike a single large capacitor in FIGS. 13A-13B.

Assuming that the switching capacitors C1 _(FLY) 204, C2 _(FLY) 206, andC3 _(FLY) 802 and the decoupling capacitor C_(OUT) 214 are large, thefollowing relationships can be derived for the two states:State0: V _(C1FLY) =V _(C2FLY) =V _(C3FLY) =V _(IN) 202−V _(OUT) 208State1: V _(C1FLY) =V _(C2FLY) =V _(C3FLY) =V _(OUT) 208where V_(C1FLY) is a voltage across the first switching capacitor C1_(FLY) 204, V_(C2FLY) is a voltage across the second switching capacitorC2 _(FLY) 206, and V_(C1FLY) is a voltage across the third switchingcapacitor C3 _(FLY) 802. These relationship can be reorganized asfollows:V _(C1FLY) =V _(OUT)V _(C2FLY) =V _(OUT)V _(C3FLY) =V _(OUT)V _(OUT)=(1/2)×V _(IN)Therefore, the reconfigurable Dickson Star SC regulator illustrated inFIGS. 19A-19C operates as a 2:1 step-down Dickson Star SC regulator.

FIGS. 20A-20C illustrate the operation of a 4:1 reconfigurable DicksonStar SC regulator when it is working in 1:1 mode in accordance with someembodiments. The switching capacitors C1 _(FLY) 204, C2 _(FLY) 206, C3_(FLY) 802 are tied in parallel to work like a single large capacitor,just like capacitors C1 _(FLY) 204, C2 _(FLY) 206, C3 _(FLY) 802 weretied in parallel to work like a single large capacitor in FIGS. 14A-14B.

Assuming that the switching capacitors C1 _(FLY) 204, C2 _(FLY) 206, andC3 _(FLY) 802 and the decoupling capacitor C_(OUT) 214 are large, thefollowing relationships can be derived for the two states:State0: V _(C1FLY) =V _(C2FLY) =V _(C3FLY) =V _(IN) 202State1: V _(C1FLY) =V _(C2FLY) =V _(C3FLY) =V _(OUT) 208where V_(C1FLY) is a voltage across the first switching capacitor C1_(FLY) 204, V_(C2FLY) is a voltage across the second switching capacitorC2 _(FLY) 206, and V_(C1FLY) is a voltage across the third switchingcapacitor C3 _(FLY) 802. These relationships can be reorganized asfollows:V _(C1FLY) =V _(OUT)V _(C2FLY) =V _(OUT)V _(C3FLY) =V _(OUT)V _(OUT) =V _(IN)Therefore, the reconfigurable Dickson Star SC regulator illustrated inFIGS. 14A-14C operates as a 1:1 step-down Dickson Star SC regulator.

The regulators in FIGS. 10-14 and the regulators in FIGS. 16-20 use amode switch matrix with switches located in different positions, but theeventual capacitor arrangements are identical. Therefore, thereconfigurable regulator 1000 is functionally identical to thereconfigurable regulator 1600.

In some embodiments, the 4:1 reconfigurable regulator 1600 can begeneralized to provide a N:1 reconfigurable regulator where N is greaterthan one. FIGS. 21A-21C illustrate a N:1 reconfigurable Dickson-Star SCregulator operating in accordance with some embodiments.

The N:1 reconfigurable Dickson-Star SC regulator 2100 can also include acapacitor matrix. The capacitor matrix can include a first capacitorsub-matrix and a second capacitor sub-matrix. The capacitors in thefirst capacitor sub-matrix are referred to as C(1, j), where the firstindex “1” refers to the “first” capacitor matrix, and the second index“j” refers to the j^(th) capacitor in the first capacitor sub-matrix.Likewise, the capacitors in the second capacitor sub-matrix are referredto as C(2, j). In FIGS. 21A-21B, the first capacitor sub-matrix includeM number of capacitors; and the second capacitor sub-matrix include Knumber of capacitors. In some embodiments, M is equal to floor(N/2), andK is equal to floor((N−1)/2).

In some embodiments, the N:1 reconfigurable Dickson-Star SC regulator2100 includes a switch matrix having a first switch sub-matrix, a secondswitch sub-matrix, and a third switch sub-matrix. Switches in each ofthese matrices are arranged serially between input voltage V_(IN) 202and GND 210.

The switches in the first switch sub-matrix are referred to as SW(1, j),where the first index “1” refers to the “first” switch matrix, and thesecond index “j” refers to the j^(th) switch in the first switchsub-matrix. Likewise, the switches in the second switch sub-matrix arereferred to as SW(2, j), and the switches in the third switch sub-matrixare referred to as SW(3, j). In FIGS. 21A-21B, the first switchsub-matrix include E number of switches; the second switch sub-matrixinclude D number of switches; and the third switch sub-matrix include Fnumber of switches. In some embodiments, E is equal to 2×ceiling(N/2)−1;D is equal to floor(N/2); and F is equal to N.

In some embodiments, a switch in the first switch sub-matrix connectstwo capacitors in the first capacitor sub-matrix. For example, C(1, p)and C(1, p+1) are connected through SW(1, p). Similarly, a switch in thesecond switch sub-matrix connects two capacitors in the second capacitorsub-matrix. For example, C(2, p) and C(2, p+1) are connected throughSW(2, p). A switch in the third switch sub-matrix connects a capacitorin the first capacitor sub-matrix to a capacitor in the second capacitorsub-matrix. For example, C(1, p) and C(2, p) are connected through SW(3,2×p), and C(1, p+1) and C(2, p) are connected through SW(3, 2×p+1).

In some embodiments, this regulator 2100 can be duty-cycled betweenState0 and State1 by turning on and off switches in the switch matrix ofthe regulator 2100.

FIGS. 21A-21B show the operation of the N:1 reconfigurable Dickson StarSC regulator 2100 in the N:1 conversion mode in accordance with someembodiments. In State0, in the third switch sub-matrix, all odd indexedswitches are off while all even indexed switches are on. Subsequently,in State1, all switch states in the third switch sub-matrix are invertedcompared to State0. All switches in the first switch sub-matrix and allswitches in the second switch sub-matrix side are turned off in bothState0 and State1. While there are additional switches including thefirst and second switch matrices, since all those switches are turnedoff, the capacitor topologies are similar to the N:1 step-down DicksonStar in FIG. 35.

To operate the N:1 reconfigurable Dickson-Star SC regulator 2100 in the(N−1):1 conversion mode, the capacitor that is connected to V_(IN) 202through the fewest switches (or, put differently, closest to the inputterminal) in the third switch sub-matrix, which is C(2,K) in FIGS.21A-21B, and the capacitor that is in the same matrix but with a onelower index, which is C(2, K−1) in FIGS. 21A-21B, can be tied togetherin parallel to operate as a single capacitor. To keep the two capacitorstied into a “single” capacitor, SW(2,D) is always on in State0 andState1. This “single” capacitor can work similar to C(1, M) in an(N−1):1 fixed conversion mode Dickson-Star SC regulator-a Dickson-StarSC regulator that is identical to a N:1 fixed conversion modeDickson-Star SC regulator without C(2, K), SW(3, F). Since C(2, K) doesnot exist independently anymore (or works with C(2, K−1)), SW(3, F−1) isturned off in both State0 and State1. C(1, M) acts as the top capacitor,so SW(1, E) acts like the top switch, and SW(3, F) is turned off in bothState0 and State1. To summarize, SW(2, D) is always on in State0 andState1, SW(3, F−1) and SW(3, F) are always off in State0 and State1, andSW(1, E) switches on and off in State0 and State1, respectively.

To operate the N:1 reconfigurable Dickson-Star SC regulator in the(N−2):1 conversion mode, three capacitors that are connected to V_(IN)202 through fewest switches can be tied together in parallel to worklike a single capacitor. In FIGS. 21A-21B, these three capacitors areC(2,K), C(1,M), and C(2,K−1). This “single” capacitor can work similarto C(2, K−1) in an (N−2):1 fixed conversion mode Dickson-Star SCregulator—a Dickson-Star SC regulator that is identical to a N:1 fixedconversion mode Dickson-Star SC regulator without C(2, K), C(1,M), SW(3,F), SW(F−1). To keep the three capacitors tied as a “single” capacitor,SW(2,D), SW(3, E−1) are always on in State0 and State1. Since C(2, K)and C(1, M) do not exist independently anymore, SW(3, F−1) and SW(3,F−2) are turned off in both State0 and State1. C(2, K−1) acts as the topcapacitor, so SW(3, F) acts like the top switch, and SW(1, E) is turnedoff in both State0 and State1. To summarize, SW(2, D) and SW(1, E−1) arealways on in State0 and State1, SW(3, F−1), SW(3, F−2), SW(1, E) arealways off in State0 and State1, and SW(3, F) switches off and on inState0 and State1, respectively.

More generally, to operate the N:1 reconfigurable Dickson-Star SCregulator in the (N−R):1 conversion mode, “R+1” number of capacitorsthat are connected to V_(IN) 202 through fewest switches in the thirdswitch sub-matrix can be tied together in parallel to work like a singlecapacitor, and operate the remaining switches as if operating the(N−R):1 fixed conversion mode Dickson-Star SC regulator.

In some embodiments, the control module is configured to perform thefollowing switch operations to operate the N:1 reconfigurableDickson-Star SC regulator in the (N−R):1 conversion mode. The controlmodule is configured to turn on the top “R” number of switches in thefirst and second matrices (e.g., R switches that are closest to theinput voltage terminal, or, put another way, R switches that have fewestnumber of switches between them and the input voltage terminal),excluding the top switch in the first switch sub-matrix SW(1, E) that isdirectly connected to the input voltage terminal. When a first switch ina first switch sub-matrix and a second switch in a second switchsub-matrix have the same number of switches between them and the inputvoltage terminal and only one of them can be included in the set of Rswitches, then the second switch in the second switch sub-matrix wouldbe selected. For example, if R is equal to 3, SW(2, D), SW(1, E−1),SW(2, D−1) are selected as the “3” switches closest to the input voltageterminal. The control module is configured to keep the R switches turnedon in both State0 and State1 to tie the top 3 capacitors in parallel.

Also, the control module is configured to turn off the top “R” number ofswitches in the third switch matrix (e.g., R number of switches that areclosest to the input voltage terminal, or, put another way, R number ofswitches that have fewest number of switches between them and the inputvoltage terminal), excluding the top switch SW(3, F) in the third switchsub-matrix that is connected to the input voltage terminal. For example,if R is equal to 3, SW(3, F−1), SW(3, F−2), SW(3, F−3) are always off inState0 and State1.

Also, when R is an odd number, the control module is configured to turnoff the top switch SW(3, F) in the third switch sub-matrix and operatethe top switch SW(1, E) in the first switch sub-matrix as if the topswitch SW(1, E) in the first switch sub-matrix is the top switch of thethird switch sub-matrix.

In some embodiments, when R is an even number, the control module isconfigured to turn off the top switch SW(1, E) in the first switchsub-matrix and operate the top switch SW(3, F) in the third switchsub-matrix as if the top switch SW(3, F) in the third switch sub-matrixis the top switch of the first switch sub-matrix.

In some embodiments, the state of the top switch is inverted compared tothe top most switch in the third switch matrix that is not always off.For example, if R is equal to 3, since R is an odd number, SW(3, F) isturned off. Also, SW(3, F−1), SW(3, F−2), SW(3, F−3) are always off.Therefore, the top switch, which is SW(1, E), is in a state that isinverted compared to SW(3, F−4), the top most switch in the third switchmatrix that is not always off.

In some embodiments, the reconfigurable Dickson-Star SC regulator can beoperated as a part of a voltage regulator system. The voltage regulatorsystem can operate in multiple interleaved phases (e.g., in atime-interleaved manner over a single period), and the reconfigurableDickson-Star SC regulator can be used to provide an output voltage inone of the interleaved phases. For example, a voltage regulator systemcan include three reconfigurable Dickson-Star SC regulators that eachoperate 0 degrees, 120 degrees, 240 degrees out of phase, respectively.

In some embodiments, the reconfigurable Dickson-Star SC regulator can beused for various applications including power management integratedcircuits (PMICs), battery chargers, LED drivers, envelope tracking poweramplifiers.

In some embodiments, the capacitance of switching capacitors (e.g., C1_(FLY) 204, C2 _(FLY) 206, and C3 _(FLY) 802) can be set to beproportional to an output current of the reconfigurable Dickson-Star SCregulator. For example, the capacitance of switching capacitors can bein the range of 0.1 nF/mA and 100 nF/mA, depending on the target powerefficiency. The reconfigurable Dickson-Star SC regulator can improve itsefficiency by using larger capacitance values.

In some embodiments, a reconfigurable Dickson-Star SC regulator can beoperated in a reverse configuration (e.g., the input node and the outputnode of the reconfigurable Dickson-Star SC regulator are switched.) Theoperational direction of the reconfigurable Dickson-Star SC regulatorcan be flexibly modified to accommodate various types of input voltagesources and output loads coupled to the input node and the output nodeof the reconfigurable Dickson-Star SC regulator.

In some embodiments, a reconfigurable Dickson-Star SC regulator can beoperated in a reverse direction to operate it as a step-up regulator.For example, an input node of the reconfigurable Dickson-Star SCregulator can be coupled to a target load (e.g., a chip) and an outputnode of the reconfigurable Dickson-Star SC regulator can be coupled toan input voltage source (e.g., a battery).

FIGS. 22-24 illustrate step-up reconfigurable Dickson-Star SC regulatorsin accordance with some embodiments. The regulator 2200 is a step-upreconfigurable 1:3 Dickson-Star SC regulator; the regulator 2300 is astep-up reconfigurable 1:4 Dickson-Star SC regulator; and the regulator2400 is a step-up reconfigurable 1:4 Dickson-Star SC regulator. Thestep-up reconfigurable Dickson-Star SC regulators in FIGS. 22-24 aresimilar to the step-down regulators in FIGS. 6, 10, and 16,respectively, except that the location of V_(IN) 202 and V_(OUT) 208 areswapped and V_(IN) 202 is lower than V_(OUT) 208.

In some embodiments, a reconfigurable Dickson-Star SC regulator can beoperated in a reverse direction to operate it as a battery charger. Forexample, an input node of the reconfigurable Dickson-Star SC regulatorcan be coupled to a power source, e.g., a power line of a UniversalSerial Bus (USB), and an output node of the reconfigurable Dickson-StarSC regulator can be coupled to a battery so that the output voltage andthe output current of the reconfigurable Dickson-Star SC regulator areused to charge the battery.

In some embodiments, the reconfigurable Dickson-Star SC regulator can beparticularly useful in charging batteries in a handheld device. Ahandheld device, such as a smartphone, can use a Lithium-Ion (Li-Ion)battery that is configured to provide a voltage output within the rangeof approximately 2.8-4.3V, depending on whether the battery is chargedor not (e.g., 4.3V when fully charged, 2.8V when fully discharged). TheLi Ion battery in the handheld device can be charged using a UniversalSerial Bus (USB). The current version of the USB power line uses 5V (andthe future versions of the USB may use even higher voltages), which ishigher than the voltage output of the Li Ion battery. Therefore, thevoltage from the USB power line should be stepped down before it can beused to charge the Li Ion battery. To this end, the reconfigurableDickson-Star SC regulator can be configured to receive the power linevoltage (and current) from the USB and provide a step-down version ofthe power line voltage (and current) to the Li-Ion battery so that theLi-Ion battery can be charged based on the voltage and current from theUSB.

In some embodiments, the above-identified configuration, in which abattery is charged using a USB power line, can be used in reverse as aUSB On-The-Go (OTG), where the battery in a first device can deliverpower to a second device over USB to charge the second device. In thisscenario, a battery in a first device is configured to deliver currentto a battery in a second device through a USB. Although the outputvoltage of the battery in the first device may be lower than the USBpower line voltage, the reconfigurable Dickson-Star SC regulator canoperate in a step-up configuration to step-up the output voltage of thebattery to that of the USB power line. This way, the battery in thefirst device can charge the battery in the second device over the USBpower line.

In some embodiments, a SC regulator, such as a reconfigurableDickson-Star SC regulator, can be operated in conjunction with anothervoltage regulator to provide a two-stage voltage regulation. FIG. 25illustrates a two-stage voltage regulation system in which a SCregulator provides the first stage voltage regulation in accordance withsome embodiments. FIG. 25 includes a regulator 2502 and a second-stagevoltage regulator 2504. The SC regulator 2502 can be any type of SCregulator, including, for example, one of reconfigurable Dickson-Star SCregulators disclosed herein. In some embodiments, the second-stagevoltage regulator 2504 can include one or more of a buck regulator, a SCregulator, a linear regulator, and/or any types of voltage regulatorscapable of providing voltage regulation.

In some embodiments, the SC regulator 2502 can be operated to provide anoutput voltage at which the SC regulator 2502 can provide a highefficiency, and subsequently regulate the output voltage of the SCregulator 2502 using the second stage regulator 2504.

For example, the reconfigurable Dickson-Star SC regulator 2502 canconvert the input voltage 202 to V_(TMP) 2506, which is a fraction ofthe input voltage 202 at which the reconfigurable Dickson-Star SCregulator 2502 can provide high efficiency. For example, V_(TMP) 2506can be V_(IN)/N, where N is the step-down ratio. Then the second stagevoltage regulator 2504 can receive V_(TMP) 2506 and regulate it toprovide V_(OUT) 208.

FIG. 26A illustrates an embodiment of FIG. 25 in which the second stageregulator is a buck converter in accordance with some embodiments. Here,V_(TMP) 2506 is regulated by the buck converter 100 in fine steps usingmultiple power switches 114, 116 and one or more inductors 108. FIG. 26Billustrates the timing diagram of signals in the regulator.

The two-stage regulator illustrated in FIGS. 25-26, also referred to asa hybrid regulator, hinges on the fact that SC regulators are good atdividing voltages across predetermined fractional values and that thesecond stage regulators, such as buck regulators, can be good atregulating across a wide range of output voltage in fine steps. Forexample, in a 12V-to-1V step-down regulator, the reconfigurableDickson-Star SC regulator 2502 can receive 12V at V_(IN) 202 and providea ⅙ step-down, thereby providing 2V at V_(TMP) 2506. Subsequently, thebuck regulator 100 can provide a subsequent regulation to regulate 2V to1V. Since this two-stage regulator reduces the voltage swing at theinternal node Vx of the buck regulator 100 to V_(TMP) 2506, which can besubstantially less than V_(IN) 202, this topology can reduce thecapacitive power loss in the buck regulator 100 due to the parasiticcapacitance at the junction 122.

FIG. 27 illustrates a two-stage voltage regulation system in which a SCregulator provides the second stage voltage regulation in accordancewith some embodiments. FIG. 27 includes a first stage voltage regulator2702 and a SC regulator 2704. The SC regulator 2704 can be any type ofSC regulators, including, for example, one of reconfigurableDickson-Star SC regulators disclosed herein. In some embodiments, thefirst stage voltage regulator 2702 can include one or more of a buckregulator, a SC regulator, a linear regulator, and/or any types ofvoltage regulators capable of providing voltage regulation.

In FIG. 27, the first stage regulator 2702 receives an input voltageV_(IN) 202, and provides as output V_(TMP) 2706 to the SC regulator2704. The SC regulator 2704 can subsequently step-down V_(TMP) 2706 tothe desired output voltage 208.

When the first stage regulator 2702 is a switched inductor regulator,the two-stage voltage regulation system of FIG. 27 can reduce theinductor resistive loss of the switched inductor regulator by operatingthe switched inductor regulator at a high switching frequency and with asmall amount of current flow through the inductor. This approach canreduce the resistive loss of the switched inductor regulator even with asmall inductor with a low inductance. Furthermore, this topology canalso reduce the capacitive loss (CV²f loss) of the switched inductorregulator by limiting the voltage swing across the switches.

In some embodiments, the first stage regulator 2702 can include only aninductor. FIG. 28A illustrates a two-stage voltage regulator in whichthe first stage regulator consists sole of an inductor in accordancewith some embodiments. FIG. 28B illustrates a timing diagram of signalsin the two-stage voltage regulator of FIG. 28A in accordance with someembodiments. Here, the first stage regulator is a single inductor 2802.One terminal of the inductor 2802 is coupled to the input voltage V_(IN)202, and the other terminal of the inductor 2802 is coupled to an inputof the SC regulator 2704. The input voltage to the SC regulator 2704 isreferred to as V_(TMP) 2706.

In some embodiments, the input voltage V_(TMP) 2706 of the SC regulator2704 is connected to one of the plates of a switching capacitor C_(FLY)2804 in the SC regulator 2704. As the SC regulator 2704 switches betweenState0 and State1 (see, e.g., FIGS. 3A-3B), the voltage potentialV_(TMP) 2706 on the top plate of the switching capacitor C_(FLY) 2804 isswitched between two voltages V₁ and V₂. Based on this operation, thefollowing relationship can be derived:V _(IN) 202=V ₁ D+V ₂(1−D)

The value of V₁ and V₂ are set by the conversion ratio of the SCregulator 2704 and V_(OUT) 208. As a result, the conversion ratiobetween V_(IN) 202 and V_(OUT) 208 can be finely controlled based on theduty cycle D and the conversion ratio of the SC regulator 2704. Theadvantage of the two-stage regulator in FIG. 28 is that a single-stageSC regulator 2704, which can only provide integer-ratio conversionmodes, can be converted into a two-stage regulator capable of providingnon-integer-ratio conversion modes, simply by adding a single inductor2802.

In some embodiments, the two-stage regulator may have a by-pass switchSWI 2806 that is configured to short the inductor 2802 in thefirst-stage regulator. The by-pass switch SWI 2806 allows thefirst-stage regulator to be turned off in case its operation is notneeded.

FIGS. 29A-29B illustrate an operation of a two-stage regulator in FIG.28 in which the SC regulator 2704 is a 4:1 Dickson Starswitched-capacitor (SC) regulator 800 in accordance with someembodiments.

In some embodiments, the second stage 4:1 regulator 800 is duty-cycledbetween State0 and State1 to provide voltage regulation, as is alsoillustrated in FIGS. 9A-9B. Assuming that the switching capacitors C1_(FLY) 204, C2 _(FLY) 206, and C3 _(FLY) 802 and the decouplingcapacitor C_(OUT) 214 are large, the following relationships can bederived for the two states:State0: V _(TMP) 2706=V _(C3FLY) +V _(OUT) 208State0: V _(C2FLY) =V _(C1FLY) +V _(OUT) 208State1: V _(OUT) 208=V _(C1FLY)State1: V _(C3FLY) =V _(OUT) 208+V _(C2FLY)where V_(C1FLY) is a voltage across the first switching capacitor C1_(FLY) 204, V_(C2FLY) is a voltage across the second switching capacitorC2 _(FLY) 206, and V_(C1FLY) is a voltage across the third switchingcapacitor C3 _(FLY) 802. These relationship can be reorganized asfollows:V _(C2FLY)=2×V _(OUT)V _(C3FLY)=3×V _(OUT)V _(OUT)=(1/4)×V _(TMP)Therefore, the second stage SC regulator operates as a 4:1 step-downregulator, and V_(TMP) 2706 swings between 3×V_(OUT) and 4×V_(OUT) inState0 and State1. The duty-cycling of the second stage regulator, aswell as the voltage swing of V_(TMP) 2706 is illustrated in FIG. 30.

Since V_(TMP) 2706 swings between 3×V_(OUT) and 4×V_(OUT), this voltageswing is regulated by the inductor 2802 to provide the followingrelationship:V _(IN) 202=(3×V _(OUT))D+(4×V _(OUT))(1−D)=(4−D)×V _(OUT)where D is a value between 0 and 1, and preferably between 0.25 and0.75. In other words, the two-stage regulator in FIG. 29 allows for thefollowing voltage relationship:V _(OUT)=(1/(4−D))V _(IN)Therefore, a voltage regulator control system can control the duty cycleD between 0 and 1 to fine-tune the relationship between V_(IN) 202 andV_(OUT) 208 beyond integer conversion ratios. In some sense, the firststage regulator and the second stage regulator in FIG. 28 have anidentical duty cycle D.

FIG. 31 illustrates a two-stage voltage regulation system in which thesecond stage regulator is a multi-phase voltage regulator in accordancewith some embodiments. The multi-phase voltage regulator in the secondstage regulator allows the first stage regulator and the second stageregulator to use independent duty cycles. This may be beneficial in somecases because the efficiency of an SC regulator may degrade when theduty-cycle of the SC regulator deviates from 0.5. By allowing the firststage regulator and the second stage regulator to have independent dutycycles, the second stage regulator can be operated at a high efficiencylevel (e.g., close to a duty cycle of 0.5) regardless of the desiredoutput voltage of the voltage regulation system.

As shown in FIG. 31, in some embodiments, the second stage SC regulatorhas two 4:1 SC regulator modules, SC_ph0 3102 and SC_ph1 3104, whereSC_ph0 3102 and SC_ph1 3104 operate with their own phases. In someembodiments, the two SC regulator modules may be 180 degrees out ofphase. The phase relationship between SC_ph0 3102 and SC_ph1 3104 isillustrated in FIG. 32 in accordance with some embodiments. In FIG. 32,the two 4:1 SC regulator modules operate at a duty cycle of 0.5, therebyachieving high efficiency.

While the two 4:1 SC regulator modules operate at a duty cycle of 0.5,the duty cycle of the switched-inductor regulator in the first stageregulator can be independently controlled. In particular, theswitched-inductor regulator can have its own duty cycle D by switchingswitches SW9 804 and SW17 3126 out of phase at a duty cycle D,irrespective of the duty cycle of the two 4:1 SC regulator modules.

For example, when both modules SC_ph0 3102 and SC_ph1 3104 operate at aduty cycle of 0.5, the voltages V1 3130 and V2 3132 at the top plate ofC3 _(FLY) 802 and C6 _(FLY) 3110 swing between 3×V_(OUT) 208 and4×V_(OUT) 208 at a duty cycle of 0.5, as illustrated in the waveforms ofFIG. 32. Since the voltages V1 3130 and V2 3132 at the top plate of C3_(FLY) 802 and C6 _(FLY) 3110 swing between 3×V_(OUT) 208 and 4×V_(OUT)208 at any given time, the switches SW9 804 and SW17 3126 can turn onand off (out of phase) at a duty cycle D to connect V_(TMP) 2706 toeither 3×V_(OUT) 208 or 4×V_(OUT) 208 at a duty cycle D, as shown inFIG. 32. This allows the first stage regulator to operate at a dutycycle D, while the second stage regulator (including the two 4:1 SCregulator modules, SC_ph0 3102 and SC_ph1 3104) operates at a duty cycleof 0.5, thereby improving the operating efficiency of the second stageregulator.

When the switches SW9 804 and SW17 3126 are duty-cycled at a duty cycleof D, the amount of time that one particular SC module is used candepend on the duty cycle D. For example, in FIG. 32, the duty cycle D isless than 0.5. Therefore, the first SC module 3102 is used less than 50%of the time while the second SC module 3104 is used more than 50% of thetime. In an extreme case, one SC module could be used 100% of the timewhile the other SC module is used 0% of the time. To accommodate suchextreme scenarios, all switches and capacitors in the two SC modules3102, 3104 may need to be sized sufficiently large so that a single SCmodule can deliver the maximum required output power—as if the other SCmodule does not exist.

In some embodiments, the switches SW9 804 and SW17 3126 can becontrolled such that each switch SW9 804 and SW17 3126 is turned on forthe same amount of time while maintaining the duty cycle of the firststage regulator. This way, the SC modules in the multi-phase regulator(the second stage regulator) are used the same amount of time regardlessof the duty cycle of the first stage regulator. This allows the switchesand capacitors in the SC modules to be about half the size compared tothe scenario in which a single SC module needs to be able to deliver themaximum required output power.

FIG. 33 illustrates the control sequence of switches that allows eachswitch SW9 804 and SW17 3126 to be turned on for the same amount of timewhile maintaining the duty cycle of the first stage regulator inaccordance with some embodiments. In a given period, the first switchSW9 804 is turned on 50% of the time while keeping the second switchSW17 3126 turned off, and the second switch SW17 3126 is turned on 50%of the time while keeping the first switch SW9 804 turned off. However,the time instance at which the period starts is determined such that thevoltage V_(TMP) 2706 swings between 3×V_(OUT) and 4×V_(OUT) at a dutycycle D.

For example, when the SW9 804 is turned on and SW17 is turned off, thevoltage V_(TMP) 2706 is coupled to V1 3130, and when the SW9 804 isturned off and SW17 is turned on, the voltage V_(TMP) 2706 is coupled toV2 3132. Therefore, by shifting the time instance 3302, the duty cycle Dduring which the V_(TMP) 2706 is at 4×V_(OUT) can be controlled. Forinstance, when the time instance 3302 is shifted to the right, the dutycycle D would increase proportionally; when the time instance 3302 isshifted to the left, the duty cycle D would decrease proportionally. Oneadditional benefit of this configuration is that V_(TMP) 2706 switchesat twice the frequency of the switched-inductor and switched-capacitorregulators. This feature can enable the use of a smaller inductor 3302without incurring additional switching loss.

Although the second stage regulator was illustrated using areconfigurable Dickson Star regulator, other types of SC regulators canalso be used for the second stage regulator in FIGS. 27-29, and 31. Forexample, the second stage regulator can include a ladder SC regulator, areconfigurable ladder SC regulator, a series-to-parallel SC regulator, areconfigurable series-to-parallel regulator, and/or any other types ofSC regulators.

In some embodiments, the two-stage regulator can be used for variousapplications including power management integrated circuits (PMICs),battery chargers, LED drivers, envelope tracking power amplifiers.

In some embodiments, the capacitance of the switched capacitor regulatorcan be set to be proportional to an output current of the two-stageregulator. For example, the capacitance of the switched capacitorregulator can be in the range of 0.1 nF/mA and 100 nF/mA, depending onthe target power efficiency. The two-stage regulator can improve itsefficiency by using larger capacitance values.

In some embodiments, a two-stage regulator can be operated in a reversedirection to operate it as a step-up regulator. For example, an inputnode of the two-stage regulator can be coupled to a target load (e.g., achip) and an output node of the two-stage regulator can be coupled to aninput voltage source (e.g., a battery).

In some embodiments, a two-stage regulator can be operated in a reversedirection to operate it as a battery charger. For example, an input nodeof the two-stage regulator can be coupled to a power source (e.g., apower line of a Universal Serial Bus (USB)) and an output node of thetwo-stage regulator can be coupled to a battery.

Various embodiments of the disclosed two-stage regulator can be used asa battery charger in a battery-operated device. For example, an outputnode of a two-stage regulator can be coupled to a battery so that theoutput voltage and the output current of the two-stage regulator areused to charge the battery.

The two-stage regulator can be particularly useful in charging batteriesin a handheld device. A handheld device, such as a smartphone, can use aLithium-Ion (Li-Ion) battery that is configured to provide a voltageoutput within the range of approximately 2.8-4.3V, depending on whetherthe battery is charged or not (e.g., 4.3V when fully charged, 2.8V whenfully discharged). The Li Ion battery in the handheld device can becharged using a Universal Serial Bus (USB). The current version of theUSB power line uses 5V (and the future versions of the USB may use evenhigher voltages), which is higher than the voltage output of the Li Ionbattery. Therefore, the voltage from the USB power line should bestepped down before it can be used to charge the Li Ion battery. To thisend, the two-stage regulator can be configured to receive the power linevoltage and current from the USB and provide a step-down version of thepower line voltage and current to the Li-Ion battery so that the Li-Ionbattery can be charged based on the voltage and current from the USB.

In some embodiments, the above-identified configuration, in which abattery is charged using a USB power line, can be used in reverse as aUSB On-The-Go (OTG), where the battery in a first device can deliverpower to a second device over USB to charge the second device. In thisscenario, a battery in a first device is configured to deliver currentto a battery in a second device through a USB. Although the outputvoltage of the battery in the first device may be lower than the USBpower line voltage, the two-stage regulator can operate in a step-upconfiguration to step-up the output voltage of the battery to that ofthe USB power line. This way, the battery in the first device can chargethe battery in the second device over the USB power line.

FIG. 34 is a block diagram of a computing device that includes a voltageregulation system in accordance with some embodiments. The computingdevice 3400 includes a processor 3402, memory 3404, one or moreinterfaces 3406, an accelerator 3408, and a voltage regulator system3410. The computing device 3400 may include additional modules, fewermodules, or any other suitable combination of modules that perform anysuitable operation or combination of operations.

In some embodiments, the accelerator 3408 can be implemented in hardwareusing an application specific integrated circuit (ASIC). The accelerator3408 can be a part of a system on chip (SOC). In other embodiments, theaccelerator 3408 can be implemented in hardware using a logic circuit, aprogrammable logic array (PLA), a digital signal processor (DSP), afield programmable gate array (FPGA), or any other integrated circuit.In some cases, the accelerator 3408 can be packaged in the same packageas other integrated circuits.

In some embodiments, the voltage regulator system 3410 can be configuredto provide a supply voltage to one or more of the processor 3402, memory3404, and/or an accelerator 3408. The voltage regulator system 3410 caninclude one or more voltage regulator (VR) modules 3412-1 . . . 3412-N.In some embodiments, one or more of the VR modules 3412-1 . . . 3412-Ncan be a reconfigurable Dickson-Star SC regulator, for example, asdisclosed in FIGS. 4, 10, and 16. In some embodiments, one or more ofthe VR modules 3412-1 . . . 3412-N can be a two-stage regulator, forexample, as disclosed in FIGS. 27-29, 31. The one or more VR modules3412-1 . . . 3412-N may operate in multiple interleaved phases.

In some embodiments, the voltage regulator system 3410 can include aswitch control module that is configured to control the switchconfiguration in one or more VR modules 3412-1 . . . 3412-N. Forexample, when the switch control module receives an instruction tooperate a 3:1 reconfigurable Dickson Star SC regulator in a 3:1conversion mode, the switch control module can be configured to controlthe switch matrix 216-228 and the mode switch SW8 402 to operate thereconfigurable Dickson Star SC regulator in a 3:1 conversion mode, asshown in FIGS. 5A-5C. As another example, when the switch control modulereceives an instruction to operate the 3:1 reconfigurable Dickson StarSC regulator in a 2:1 conversion mode, the switch control module can beconfigured to control the switch matrix 216-228 and the mode switch SW8402 to operate the reconfigurable Dickson Star SC regulator in a 2:1conversion mode, as shown in FIGS. 6A-6C. In some embodiments, theswitch control module can be synthesized using hardware programminglanguages. The hardware programming languages can include Verilog, VHDL,Bluespec, or any other suitable hardware programming language. In otherembodiments, the switch control module can be manually designed and canbe manually laid-out on a chip.

The computing device 3400 can communicate with other computing devices(not shown) via the interface 3406. The interface 3406 can beimplemented in hardware to send and receive signals in a variety ofmediums, such as optical, copper, and wireless, and in a number ofdifferent protocols, some of which may be non-transient.

In some embodiments, the computing device 3400 can include userequipment. The user equipment can communicate with one or more radioaccess networks and with wired communication networks. The userequipment can be a cellular phone having telephonic communicationcapabilities. The user equipment can also be a smart phone providingservices such as word processing, web browsing, gaming, e-bookcapabilities, an operating system, and a full keyboard. The userequipment can also be a tablet computer providing network access andmost of the services provided by a smart phone. The user equipmentoperates using an operating system such as Symbian OS, iPhone OS, RIM'sBlackberry, Windows Mobile, Linux, HP WebOS, Tizen, Android, or anyother suitable operating system. The screen might be a touch screen thatis used to input data to the mobile device, in which case the screen canbe used instead of the full keyboard. The user equipment can also keepglobal positioning coordinates, profile information, or other locationinformation. The user equipment can also be a wearable electronicdevice.

The computing device 3400 can also include any platforms capable ofcomputations and communication. Non-limiting examples includetelevisions (TVs), video projectors, set-top boxes or set-top units,digital video recorders (DVR), computers, netbooks, laptops, and anyother audio/visual equipment with computation capabilities. Thecomputing device 3400 can be configured with one or more processors thatprocess instructions and run software that may be stored in memory. Theprocessor also communicates with the memory and interfaces tocommunicate with other devices. The processor can be any applicableprocessor such as a system-on-a-chip that combines a CPU, an applicationprocessor, and flash memory. The computing device 3400 can also providea variety of user interfaces such as a keyboard, a touch screen, atrackball, a touch pad, and/or a mouse. The computing device 3400 mayalso include speakers and a display device in some embodiments. Thecomputing device 3400 can also include a bio-medical electronic device.

It is to be understood that the disclosed subject matter is not limitedin its application to the details of construction and to thearrangements of the components set forth in the following description orillustrated in the drawings. The disclosed subject matter is capable ofother embodiments and of being practiced and carried out in variousways. Also, it is to be understood that the phraseology and terminologyemployed herein are for the purpose of description and should not beregarded as limiting.

As such, those skilled in the art will appreciate that the conception,upon which this disclosure is based, may readily be utilized as a basisfor the designing of other structures, apparatuses, systems, and methodsfor carrying out the several purposes of the disclosed subject matter.It is important, therefore, that the claims be regarded as includingsuch equivalent constructions insofar as they do not depart from thespirit and scope of the disclosed subject matter.

Although the disclosed subject matter has been described and illustratedin the foregoing exemplary embodiments, it is understood that thepresent disclosure has been made only by way of example, and thatnumerous changes in the details of implementation of the disclosedsubject matter may be made without departing from the spirit and scopeof the disclosed subject matter, which is limited only by the claimswhich follow.

We claim:
 1. A voltage regulator configured to receive a first voltagesignal and provide a final voltage signal based, at least in part, onthe first voltage signal, the voltage regulator comprising: aswitched-inductor regulator consisting of an inductor, wherein a firstterminal of the inductor comprises an input terminal of theswitched-inductor regulator configured to receive the first voltagesignal, and a second terminal of the inductor comprises an outputterminal of the switched-inductor regulator configured to provide anintermediate voltage signal; a step-down regulator comprising an inputterminal configured to receive the intermediate voltage signal from theoutput terminal of the switched-inductor regulator, a switch matrix, aplurality of capacitors, and an output terminal, configured to providethe final voltage signal; and a control module configured to cause theswitch matrix in the step-down regulator to alternate between a firstconfiguration and a second configuration to arrange the plurality ofcapacitors in a first arrangement and a second arrangement,respectively, with a predetermined duty cycle, thereby also duty-cyclingthe inductor in the switched-inductor regulator.
 2. The voltageregulator of claim 1, wherein the switched-inductor regulator isswitchless.
 3. The voltage regulator of claim 1, wherein, when theswitch matrix is in a first configuration, the intermediate voltagesignal is at a first voltage level, and when the switch matrix is in asecond configuration, the intermediate voltage signal is at a secondvoltage level.
 4. The voltage regulator of claim 3, wherein the firstvoltage level is a first fractional multiple of the final voltagesignal, and wherein the second voltage level is a second fractionalmultiple of the final voltage signal.
 5. The voltage regulator of claim1, wherein the step-down regulator comprises a Dickson Star switchedcapacitor regulator.
 6. The voltage regulator of claim 5, wherein theDickson Star switched capacitor regulator comprises a reconfigurableDickson Star switched capacitor regulator.
 7. A voltage regulatorconfigured to receive a first voltage signal and provide a final voltagesignal based, at least in part, on the first voltage signal, the voltageregulator comprising: a switched-inductor regulator consisting of aninductor, wherein a first terminal of the inductor comprises an inputterminal of the switched-inductor regulator configured to receive thefirst voltage signal, and a second terminal of the inductor comprises anoutput terminal of the switched-inductor regulator configured to providean intermediate voltage signal; a step-down regulator having an inputterminal configured to receive the intermediate voltage signal from theoutput terminal of the switched-inductor regulator, and an outputterminal configured to provide the final voltage signal, wherein thestep-down regulator further comprises: a first switched capacitorregulator module comprising: a switch matrix comprising a first switchconfigured to couple the first switched capacitor regulator module tothe input terminal of the step-down regulator, and a plurality ofcapacitors; and a second switched capacitor regulator module comprising:a switch matrix comprising a second switch configured to couple thesecond switched capacitor regulator module to the input terminal of thestep-down regulator, and a plurality of capacitors; and a control moduleconfigured to: cause the switch matrix in the first switched capacitorregulator module to alternate between a first configuration and a secondconfiguration to arrange the plurality of capacitors in the firstswitched capacitor regulator module in a first arrangement and a secondarrangement, respectively, with a first duty cycle, cause the switchmatrix in the second switched capacitor regulator module to alternatebetween a third configuration and a fourth configuration to arrange theplurality of capacitors in the second switched capacitor regulatormodule in a third arrangement and a fourth arrangement, respectively,with the first duty cycle, and cause the first switch and the secondswitch to alternately couple the first switched capacitor regulatormodule and the second switched capacitor regulator module at a secondduty cycle.
 8. The voltage regulator of claim 7, wherein the firstswitched capacitor regulator module and the second switched capacitorregulator module operate out-of-phase.
 9. The voltage regulator of claim7, wherein the first switched capacitor regulator module and the secondswitched capacitor regulator comprise an identical switched capacitorregulator topology.
 10. The voltage regulator of claim 7, whereinalternately coupling the first switched capacitor regulator module andthe second switched capacitor regulator module at the second duty cyclecauses duty-cycling of the inductor in the switched-inductor regulatorat the second duty cycle.
 11. The voltage regulator of claim 7, whereinthe second duty cycle is 0.5.
 12. The voltage regulator of claim 11,wherein the control module is configured to determine a time instance atwhich to begin alternate coupling of the first switched capacitorregulator module and the second switched capacitor regulator module toprovide a desired duty cycle of the switched-inductor regulator.
 13. Thevoltage regulator of claim 1, wherein the inductor is provided as adiscrete component on-package or on-board.
 14. An electronic systemcomprising: a voltage regulator according to claim 1; and a target loadsystem coupled to the voltage regulator, wherein the output terminal ofthe step-down regulator in the voltage regulator is coupled to thetarget load system.
 15. The electronic system of claim 14, wherein thetarget load system includes a battery and the voltage regulator isconfigured to receive the first voltage signal from a power line of aUniversal Serial Bus and to provide the final voltage signal to thebattery.
 16. The electronic system of claim 14, wherein the target loadsystem comprises a System on Chip (SoC), and the SoC and the voltageregulator are packaged in a single SoC package.
 17. The electronicsystem of claim 14, wherein the target load system comprises a System onChip (SoC), and the SoC and the voltage regulator are provided on aprinted circuit board (PCB).
 18. An electronic system comprising: avoltage regulator according to claim 1, wherein the voltage regulator isconfigured to operate in a reverse direction in which the outputterminal of the step-down regulator in the voltage regulator is coupledto an input voltage source and the first input terminal of theswitched-inductor regulator is coupled to a target load of the voltageregulator.
 19. The electronic system of claim 18, wherein the electronicsystem operating the voltage regulator in a reverse direction isconfigured to operate the voltage regulator as a step-up regulator. 20.The electronic system of claim 19, wherein the output terminal of thestep-down regulator is coupled to a battery and the input terminal ofthe switched-inductor regulator is coupled to a power line of aUniversal Serial Bus.